@ploppo: The musics are in the "p0data61" archive. You can replace them using the Unity Assets Viewer (in the "Tools" menu). Only .ogg files are accepted. Incinerator's answer is more complete, if you want to change some the musics of individual battles.
Also, the battle spots are still there, just displayed better (there was only the first 4 battles in each spots before and spots at the same place were not shown together).
Update to v0.40:
- Improved the text changing window:
--- Fixed the crash of the PSX version,
--- Added a proper preview of most Steam text opcodes,
--- Allow to change all the languages on the same window,
--- Compute the dialog bubble size, approximately.
- Added a language link between scripts (AI scripts, World Map scripts and Field scripts):
--- When languages are linked, any modification on the script of one language also applies to the linked languages,
--- Except for dialog text IDs, the scripts of linked languages are the same (you can choose the translations of each text ID),
--- By default, if two language scripts only differ by the text IDs of the dialogs, they are linked,
--- The scripts batch exported are exported in all the languages checked in the "Preferences".
- Added a preview for the item icons in the Steam version (it was already there in the PSX version).
- Improved a bit the display of the World Map Battle Spots.
- Fixed some bugs (crash for some .hws files, crash when editing scripts after adding/removing a function, crash when trying to edit the "Opening-For FMV" Field...).
So, with this new version, you can, without too many troubles, create mods that are compatible with all the languages.
As I said, you can't automatically translate the texts right now, but it will be possible eventually (keeping in mind that it will be nowhere as good as true translations ; it will be about "google-translate" quality and manage the opcodes of the translations more easily). I didn't add a way to import PSX texts in Steam or vice versa. I'm not sure if it will be a thing one day (well, if really I don't have anything more to do).
Also, about the "STRT" opcode, it is updated when clicking on the "Auto-Size" button but it's not very important to have a precise width (the height is just the number of lines). If the specified width is too short, the game automatically choose the best fitting width.
It is however extremely important to have exactly one STRT opcode at the start of all the texts (at least in the "Texts" panel), even in texts that are not actually used.
Also, I tweaked the way that 3D models are imported, especially when custom model hierarchy are used, but I couldn't make everything work unfortunatly :/
I saw that replacing the 3D models of main characters is quite complicated (even swapping models) but it is possible: it needs to really make it perfect to have the good animations (so, let's say you use Quina's model instead of Zidane's, you'd need to rename the animations of Quina to fit the names of the animations of Zidane, not to mention to import everything properly with the right path names)... I'm not sure if I can make the process easier because it seems very dependant to what the engine expects... and when there is a dummy animation together with the model in the p0data4 archive, it has to be imported as well (for some reason, it's important to have this dummy animation when it's there by default).
Accessory, enemy and NPC models are much easier to change than models of the main characters (for battles, there's an additional problem since normal battle models and trance battle models share their animations).
EDIT: I forgot to add. About script languages that are linked and those that are not:
Most of the times Field scripts are the same between languages except for minor differences (but sometimes not so minor).
1) The Japanese version is not often linked to others because the buttons used are not the same. In particular, most of the time, when the script awaits a "Confirm" or "Moogle" button in the international versions (when dialog bubbles are handled by the script, for instance), it awaits a "Cancel" or "Moogle" button instead in the Japanese version.
2) In the Japanese and US versions, some "Wait" times are higher than in the other versions (surely to catch up with the PAL/NTSC frame rate). It is not always the case, far from that, but it may happen that a "Wait( 60 )" in the US/Japanese version is a "Wait( 50 )" in the European versions.
3) Dummy differences: it happens sometimes that dummy lines, with no effect, are present in some languages and not in the others. An example of this is the Chocobo Forest's UK script where an extraneous local variable is set up but never used (as part of the functions dealing with the display of the "Chocobo Forest" title tiles).
4) Real and important differences: there are a couple of real differences between the different languages. The most known is the reward of the Blank swordfight minigame (there is no static reward of 10000 gil when performing a 100/100), but there are also titles tiles that are displayed a bit differently, or some "Wait" lines added in some cutscenes... The AI script of Ragtime Mouse is also different in the US language because, contrary to all the other versions, the questions are displayed in 2 successive dialogs in US instead of 1 dialog with two lines.
Even though, it is usually safe to force the link on all the languages (except for the button mapping in Japanese that can be troublesome for people used to it). If you do force the link, you'll have to verify that dialogs used in the scripts are using the correct translation (as you may have noticed, the number of texts varies from language to language: some unused texts are removed/added in some versions, creating a shift in the text IDs).
I will now work on Alternate Fantasy for a while. I'll make an international version first, but then I'll also work on the mod ; I'm planning to only work sparsely on HW while doing that.
Also, I have once again changed a lot of things related to .hws file format (for script and text datas) ; I have done tests to check if that goes without bugs and didn't find any, but everything is possible. So I advise you to have copies of you .hws files (anyway, these files are so low-sized that I advise to have backups of them in any case).