Unlike PAF, PAF Companion is just for use with English characters. I thought there might be an exception in the case of other western Eurpean languages. So I experimented by adding to my birthplace üß (u with umlaut,and the German double s as in Strasse/Straße) As I expected, PAF made it simple using the F7 key. But as a feared, the letters ü and ß disappeared in Companion.
The work around would be to use File > Save As to save a new copy of your database, and then using Tools > Global Search and Replace to replace ü with ue and ß with ss, as these are the alternate spellings used in German.
I am not sure whether this forum supports the German characters. If not, this message will be somewhat garbled.
Your project is not going as smoothly as you hoped, is it?