I lived in Germany as a US soldier from 1979 to 1994, with a brief 9-month side trip to Ft. Hood thrown in in 1982. Thought about retiring there, but that didn't pan out.
I hadn't heard about the German language proficiency exam to maintain a residency visa until now - it must be a relatively new thing. (Backlash for the Muslim and East European invasion post-Reunification?)
My then-wife and I used both languages at home, and I had passed the DLI language exam in German enough for the language identifier, so if that requirement had existed then I wouldn't have had any trouble.
But yeah -- imagine the uproar if a similar requirement existed here.
The DUmmies and their Utopia.....