Hey, registered just to talk a bit. Was considering replaying FFVII and wondering if a fan retranslation had happened yet, glad to see someone is working on it.
I've just got a few general suggestions and comments, and I don't have time to play through the entire game with the latest script or read this entire 70 page thread, so bear with me if any of these points have already been addressed.
1. Formatting: I'm not sure if there's a technical reason for indenting the second and third lines of dialogue, but I would suggest eliminating the indent if possible. Likewise, the use of quotation marks within dialogue windows is a convention that has been dropped from modern Final Fantasy localizations, and I would suggest removing them as well. These changes would serve to make the dialogue quite a bit more readable.
2. Grammar: As a general rule, always use proper grammar. Even illiterate people are usually able to speak with some semblance of correct grammar. If a character is dumb, carefree, backwoods, etc., portray it through unique dialect, idiolect, slang, or jargon. Intentionally including bad grammar can distract the reader, especially when it's not obviously intentional.
3. Canon / non-Canon: I understand that, in many ways, you want to produce your very own localization, ignoring the shoddy original translation and any resulting adopted canon, while referring to the official English translations available in Japanese guidebooks -- and I totally respect that. I also really like that you're including options to retain official English terminology.
For me, the ideal translation would be an attempt to create the modern translation that Square Enix itself would make, taking into account the conventions established in in the more recent Compilation titles.
For example, staying true to the idiolects established for characters like Barret, Cid, Cait Sith (and Reeve's parents), and Reno, cross-referencing terms with those appearing in the new titles, and retaining perhaps just a handful of iconic terminology, while correcting/changing everything else as needed. Skimming the thread it looks like you intend to do that, so kudos!
I bring this up only because I'm not sure of exactly what the differences between your localization and the "localization but with original/canon names" are.
4. General localization notes/suggestions while looking at your non-dialogue spreadsheet:
SOLDIER - Should probably be rendered all-caps, as has been the staple in both English and Japanese, to help clarify its status as a named organization and to distinguish it from other possible uses of "soldier," with the exception of the Golden Saucer event where it ties in with Cloud's job.
グリン / グリングリン / クリン - Likely puns on "Gysahl Greens." I'd suggest naming the Guy, Saül, and Chloé. They're all French; Guy and Saül together sound like "Gysahl" and Chloé means "green sprouts." That's just my own pun; yours are also fine.
長老ブーガ - I'd suggest leaving this one as Elder Bughe, partially because "Buga" doesn't do a very good job of conveying the likely connection to Bugenhagen, and it's also one of the few names that was changed between English versions.
悪竜王 ヴァルヴァドス - Vorvadoss is pretty likely given its description, and that's the Japanese transliteration of the Mythos entity.
黒マントの男 - Simplify to "Man in Black," as per the English translation used for the reissued soundtrack.
神羅兵 - Officially localized as "Shinra Troop(s)" in Crisis Core, likely to help distinguish them from SOLDIER by avoiding the word "soldier" altogether. Shinra's Security Department troops are also referred to as infantry, in general.
モス - I'd go with Moss over Moth. Moss makes more sense as a Chocobo name, even if only slightly.
テクニカ - Should be Technica, not Technique.
ブイ, エックス, ゼット - I'd suggest "Vee," "Eks," and either "Zee" or "Zed," perhaps depending on American/British English. Just for fun, y'know.
ピッツァ2000 - I'd suggest P-ZA 2000, to give it more of a "mechanical parts number" look while keeping the "pizza" reference.
General formatting suggestion for locations: use "Area - Sub Area" instead of "Area, Sub Area," as per modern Final Fantasy conventions.
ロケットポートエリア - I'd keep this as Rocket Port Area. My assumption is that this is a callback to airship technology, since ships dock in ports. In this universe I could see people thinking of the launch pad as a port for rockets. "ロケットポート" is also a term that's unique to FFVII.
番街 - Jumping ahead a bit here: I'd strongly suggest keeping it as "Sector." Not only does it sound iconic, but it's already synonymous with district and is a mathematical term referring to a portion of a circle dived by two radii and connected by an arc, which is how the Midgar Sectors are actually divided up (like pieces of pie).
4番街プレート内部 - I'd suggest using "Sector 4 Plate Interior." When you're referring to architecture, the term "interior" sounds a bit more professional, and besides, "Plate Interior" is used in Crisis Core.
コンドルフォートふもと, 絶壁のふもと - "Base of Fort Condor" and "Base of the Cliff." Base is the more frequently used term when referring to the base of a cliff or mountain. It also sounds more technical and less literary, which better suits the function of a "map" / "location information" header.
大空洞火口 - "Great Cave Crater." This is not specifically referring to the Great Northern Cave, and is also referred to as the Northern Crater (北のクレーター), or simply the Crater (クレーター) at various points in the story. According to Crisis Core, the crater contains another, even larger network of caves, called the Great Cavern of Wonders (驚異の大洞窟) -- note the clever localization of different "cave" kanji as cave/cavern that they did in CC.
大空洞 - "Great Cave," sometimes also called the Great Northern Cave (北の大空洞). A cave is by definition a cavity in the earth, particularily one with a network of tunnels, and as outlined above, this refers to a specific cave within the Northern Crater. So, there's no need to change "cave" to "cavity" or "crater." You could also consider just following suit with the official English localizations, which drop the "Great" rather than the "Northern" (北の) when referring to it by shorthand, leaving you witht the more iconic "Northern Cave".
_番街駅ホーム - Simply "Sector _ Station," as referred to in Crisis Core.
ロケット村 - Village is more accurate, but if I'm being honest, I like Rocket Town way better as a localization.
番街 - Keep as "Sector." See above explanation.
_番街スラム - Keep as just "Sector _ Slums," without the comma. That's the name of the are, not a sub area within the "Sector _" area, if you get what I mean. There are areas within the slum that would be the sub areas.
ミッドガル8番街地下 - "Midgar - Beneath Sector 8" would be my suggestion for this, not sure if there's room.
シルドラ・イン - "Syldra Inn," a likely reference to Syldra (シルドラ), Faris's pet sea monster from FFV. How it relates to an inn in Cosmo Canyon, though Nomura did work on the monster designs for FFV.
神羅ビル・1階ロビー - Formatting should probably be "Shin-Ra Bldg. - 1F Lobby" instead of "Shin-Ra Bldg. 1F, Lobby," and same with the other locations within the building.
古代種の道具屋 - A 道具屋 is actually a "Second-Hand Shop" or "Curio Shop," which I suppose implies that the old man is reselling goods that were sold to him, rather than it actually being any sort of "general store." I personally prefer "Curio Shop," though he isn't selling any curios.
時の大穴 - I feel like there has to be an English pun that would better convey this. I'm leaning towards "Time Sinkhole."
愛の巣箱, 恋人の巣箱 - "Lovers' Hive" and "Honey's Hive," instead of "Love Nest" and "Lover's Hive," maybe?
おしおき部屋 - I'd suggest maybe simply "The Dungeon," evoking the obvious BDSM connotation.
武器屋 - Splitting hairs here, but I suggest using "Weapon Shop," as per Final Fantasy conventions. If you want to break conventions, I'd suggest "Arms Dealer."
ウータイ五強聖の塔 - The official localization for the group in Crisis Core is "Five Saints," which I think better conveys the original name. If you have to choose, I think "Pagoda of Five Saints" looks bette than "Pagoda of the 5 Saints," and gives off a touch of that Asian mysticism vibe, but that's just me.
十字手裏剣 - In FFXI this is localized as "Juji Shuriken."
突撃ラッパ - "Battle Trumpet" or "War Trumpet," both have been used in official localizations now. Battle Trumpet was used the most recently, in Airborne Brigade, but that just cribbed the translation from the original FFVII. I might lean towards "War Trumpet."
不倶戴天 - This is an intersting one, being a yojijukugo. It has two meanings, one being "Nonconformist" and the other being "Mortal Enemy," while the literal kanji meaning is "Never Together Under Heaven." I don't think there could ever be a perfect translation for this, but "Eternal Nemesis" sounds badass.
ギヤマンヘアピン - This could probably have a more accurate translation. It refers to faux diamonds, IE glass cut in the style of a diamond. "CZ Diamond Hairpin" might be closer to what this is trying to convey, though less literally accurate.
方天畫戟 - This is apparantly referred to as "Sky Piercer" in contemporary translations of The Water Margin, from which the name originates. Worth consideration.
グローランス - "Radiant Lance," this is a recurring lance in the Final Fantasy series and is pretty consistently translated as such in modern localizations, though "Glow Lance" is used a few times.
天の叢雲 - Rendered with hyphens as "Ame-no-Murakumo" in FFXII. Worth consideration.
風魔手裏剣 - Just "Fuma Shuriken" in modern translations, Hepburn be damned.
ミスリル - "Mythril" is the established English translation across the entire franchise. I say keep it that way, regardless of Tolkien.
オーガニク - "Ogrenix" / "Organyx" -- there is absolutely no consistency here in localization and the latter is more recently used (FFXIII). The Japanese fans have no idea of exactly what it's supposed to mean, either. I've always thought that it's supposed to be "Ogrenix," as a parallel to the recuring "Ogrekiller" axe (as opposed to Nyx, which is the name of a Greek goddess).
パルチザン - "Partisan," another one of those recurring weapons with consistent translations and is the most commonly used variant of the word in general use. Just because the Japanese uses ザ doesn't mean you need to follow suit.
円月輪 - "Moonring Blade," it's now pretty consistently localized as such across the Final Fantasy series.
青龍偃月刀 - Like Sky Piercer, you could opt for English. "Green Dragon Glaive" or "Dragon Glaive," possibly if that fits. Probably doesn't.
Wマシンガン - Might not be enough room, but "Dual Machinegun" instead of Double might work. They're using "Dualcast" as the official localization of W-Magic these days.
軍手 - Yes, made out of cotton, but the term refers to work gloves (made of strong cotton). I'd suggest keeping "Work Gloves."
蛇矛 - If you go Chinese, "Shemao," otherwise "Snake Lance" or "Serpent Lance." It was weilded by Zhang Fei in RotTK.
And with that, I've run out of time to go through stuff.
I may post more suggestions when I have more time.