I seriously doubt that story as the Germans are very efficient and straight laced.
We musst have ze paperz kinda thing.
The UK CAA? They actually answer emails.....unlike a certain Federal Administration in the USA


So here’s my question: You’ve been given a certificate by lazy Santa over here and now you’ve got to take a checkride with a Fed who is most likely only legally not practically b-a-r-e-l-y current in a light single let alone proficient in giving checkrides.
How is that any better?

As far as out foreign friends that need to come back and take a ride....
If you have a foreign conversion based on a US certificate (that has no expiration date) a foreign aviation administration will have no knowledge of any certificates that have been declared ‘invalid’ or otherwise suspended or revoked. These data bases are not connected and information is not shared or disseminated.
Yea for European privacy laws.
So you have a valid Europa-land conversion and your US certificate is at the bottom of a drawer unless it needs to be carried.

Rampcheck:
Papiere und schnell!
Hands over EASA conversion and US certificate.