So, just curious but how difficult is it to attempt a proper translation on this? I saw that there's a tool called Translator ++ that's used specifically for RPG maker games, but I also saw that you'll need the source files from the dev to do the translation. Is that true, or can you translate a game without needing to go to the dev?
If by "proper translation" you mean a manual translation, then the issue isn't so much that it's difficult, but that it takes a
long time. Not only is there a
lot of text in a game, but it's spread around all over the place, which makes it more tedious to translate than a regular text. RPGM also has a lot of redundancies (e.g. "replay" functions in scene viewers are actually complete duplicates of the scene, stored in a different part of the code than the original), so ironing out inconsistencies isn't exactly a cakewalk. Moreover, you have to do a lot of typesetting: a line in RPGM cannot be more than 54 characters long (including punctuation), otherwise it goes off-screen, to say nothing of centring effects which are occasionally used. Translator++ is not a good tool for doing manual spacing, so it's likely you'll have to play around inside the .json files directly.
You don't need the dev's source files for T++; all you need is an untranslated Japanese version of the game, but if your goal is to use T++ to machine-translate the whole game, then the end result won't be better than what we currently have.