Nazi Concentration Camp
Call it whatever you like, as long as it's not called Polish. You can say "in Poland" but use the correct adjective to describe its characteristics. So the most accurate description would be “concentration camp of Nazi Germany in Poland.”
The fact that it was constructed by Nazi Germans on Polish soil does not make it Polish. This is where the copyright rights come into play. If a German citizen invents something while residing abroad, does it make it a German or the host company invention? Or is it just that person’s invention?
You can split hair into four if you like, but the basic truth is black and white I believe. People like to make everything circumstantial and relative just because then there is no one to blame or take responsibility.
So another question is: What nationality were the Jews who lived in Poland or live in Poland? Are they Polish or Jewish? Or can they be possible both?
'latitude of the English language'
Maybe, but when you hear "British military base" you see Brits building and running it, don't you?