There is another update with many improvements coming very soon. :)
For German language a potential problem is the code (dictionary compression, keyboard, font) does not support special characters like umlaut, etc. Everything is built around the 26 English letters.
If you have words that are limited to those criteria then it is possible.
Given the above, if you have the two lists of words (Answer words and Remaining 5-letter words) then perhaps I can try to make a build.
You are welcome to try making the changes yourself, but it may be easier if I do them.