For those having the problems with unfound image files in game: this may be linked to some locale/emulating issues (like said in "installation" spoiler and basically spammed by some people) but, since this traduction seems incredibly rushed and only some of the file contents and not their names nor their references were tweeked in the slightest (at least in the cases of most usable cgs) the problem most likely comes from changing the file names BEFORE runtime, AKA while unzipping, hence why the "prerequisites" explained in the "installation" folder most likely won't be enough.
You need a compressed-file manager that can handle different languages. Since a lot of the more popular ones (like Winrar) only understand the key tables by default(you can add some language modules for some to "fix" them) they used on installation, changing locale has a high chance to not work, since it won't change with it, while some others will fit the system language, hence why it can work by changing system locale for some people while some others can't.
So, if using locale emulator isn't working and gives you the same error, considering looking into getting a compressed-file manager that can support eastern characters, or tweek your current one so it can. To make it clear: you do NOT need to change your system locale ANYTIME for these games if you use locale emulator in japanese on a game that you unzipped with a program that supports the characters it uses. The reason some people will try to convince you this is not the case is because this may work in certain occasions, but it is uncertain and fixing the unzipping process directly will make it easier for you and, most importantly, will make so that you won't have this kind of problem again, even if you deal with some pretty sketched-up traductions.