The game released in 4 languages: English; French; German; and Spanish. The vast majority of the game files are the same between releases, but you need to have the following 3 files that are specific to the language you use:
"\art\frontend\scrooby\resource\txtbible\srr2.p3d" - This is the file that contains all text in the game. It's possible to get one file that supports all languages.
"\simpsons.exe" - The main executable is hard coded as to which language it uses.
"\dialog.rcf", "\dialogf.rcf", "\dialogg.rcf" and "\dialogs.rcf" - Each one contains the dialog for a specific language (dialog is English, dialogf is French, dialogg is German and dialogs is Spanish.
Whilst we don't support piracy at Donut Team, you have a copy of the game and I don't mind helping you get the required files to change your language. If you join our Discord Server, I can share the files.