Unfortunately, this software was trained on an English-language dataset. I do not have access to a compatible German version. If you like, I could patch the app to automatically map ä,ö,ü,ß to ae,oe,ue,ss. But I know that may not be a particularly satisfying solution.
Can I ask if you’re using a copy of the app built from source code purchased here, or simply the prebuilt version from Github? Only the latter should have a ~50 character limit.