As an American immigrant in Germany, I encounter it somewhat regularly and it still doesn’t matter.

It was a bit of a problem when they thought I forged my covid vaccination card, because I got a shot on January tenth or something. I would then explain that I’m American and we do that. 80% of the time, they had no more questions, 20% of the time I’d show my drivers license birthday for proof (luckily I was born after the 12th).

The things that are actually problematic are the unknown tools used for my dental work (my implant screw is going to need to get a custom screwdriver made for it), and understanding temperature at an intuitive level. I understand the common weather numbers, but do I want coffee that’s 55 degrees or 70 degrees? No idea until I convert. Luckily, it’s the easiest conversion to do.