I noticed that ボトムスウェル should be Bottom Swell. He's probably named after his main attack, since a swell is a wave that has no local origin. It's probably a variation on "ground swell".
フラワープラング is probably Flower Plunge. It usually ends in a ji, but it could be mistaken for sounding like "ung". It's pretty common,
フォールランダ is Fall Rangda. The "Fall" part of the name could be a spelling of something else that looks like it has a similar pronunciation to "fall". "Foul", possibly, considering it's just four with an l added, on the surface. It's weird that it has four legs...
バジガンディ is probably Basilisk Gandhi, thanks to Gemini,
. Baji are the first two symbols for basilisk, but could also stand for bhaji, so it seems like a pun.
ギロフェルゴ could be Guillofell Ghost. Sometimes ゴ is used as shorthand for ghost...
マゴグランガラン is possibly Grand Garan. Garan is a temple, but it's a temple or temple complex usually made of smaller temples like a Matryoshka doll has several smaller dolls in it.
グラシュトライク is definitely Gura Strike. シュト is used to shorten Suto to St, giving you Strike. グラ could be short for グラグラ for unstable. Or it could be short for ground.
ジェジュジェミ has to be Jeju Jaemi (제주 재미) or something close in Korean. It's a Korean-based phrase with all the j's (say that 3 times fast). Jeju is an island that's a top vacation spot in South Korea. Roughly translates as "Jeju Fun". Since it's found in Wutai, a vacation spot in FF7, it might be related.
ジェミニスミー is directly Geminis Me. I wonder if they were going for Geminice Me, like a pat on the back for making her, but didn't want it overly obvious.
ゲルシュメルゼ is probably right as Gel Schmelze.
, Yellow Melt.
キュルビヌュ is strange. It sounds like an amalgation of Kill and Cube that rhymes with "killer bee". Nuu might be a sound effect... "Killuby ~Woo~"?
キュビルデュヌス is also weird, "Cubil Dunus".
It looks like "Cubile duonus" in Latin, possibly. Cubile can mean "hive", and duonus is an old Latin form of bonus, which can mean "brave" or "of honor". Seems likely, since I can't find any other word for "Dunus".
Kyubiru could be on-yomi pronunciation of kyu-bi-ru. None of the combinations I made had any sense to me...
マドゥジュ seems to be Madhu Ju. Madhu can refer to the demon, but can also mean something honeyish or liquid-like, since it's a swamp creature. Possibly मधु जू. This one has me stumped.
マグナード is probably マグナー奴 for Magna Slave. He's weak to gravity, so it's likely that.
プドゥレア might be Latin for Pudor Rea combined as Pudorea. Pudor means "a sense of shame", or shyness, and rea is "guilty of". Possible, since it's in a shell...
リルフサック could be Lil 芙 Saccus for Lil Lotus Saccus. The first two symbols transcribe lil, lill, or rill. フ has to be an on-yomi spelling of a kanji symbol, and サック is based on sacc, a loanword that was taken from saccus in Latin.
ヴァギドポリス might be Vagido polis, Portuguese/Spanish for moans/wails and Latin for city (many). Those were the only two languages that vagido made sense.
ゼムゼレット - The Muselet fits very well, but probably isn't it. It's probably a shorthand form based on Simon the Zealot, Sim Zealot.
ゼネネ is tough. ネネ could be short for ねるねる, for slimy. Possibly Zenenet, Egyptian goddess of beer, but probably not. It could be a name based on "gene".