You can edit the German translations here:
C:\Program Files (x86)\Stardock\Groupy\lang
Open Notepad (or any text editor) as admin as that directory requires it:
Make the edits, save, refresh the UI, and see that they work.
Noted what you edited in the following format:
Line #: 'Text.......'='Old text'
Line #: 'Text......'='New text'
I'll review it with possible barter compensation for your efforts.
Thanks for any time you care to put into this.
Stardock Support Manager