[marcus0x62]

I wouldn’t use those phrases at all to convey those ideas. Instead of:

“In such kind of language discussions, I often see that in the USA vs Germany, there seems to be a quite different understanding of fluency in the native languages”

I might write:

“When discussing language fluency, I often see that there is a significantly different perspective between Americans and Germans”.

Instead of “In the USA, you are considered to be a fluent (English) speaker when you can talk somewhat freely with the fellow countrymen”

I might write: “In the USA, you are considered to be a fluent English speaker when you can speak comfortably with other Americans”.

There, of course, many different ways to write those sentences. I’m not saying my examples are the best options, or that yours are wrong in the sense of being technically incorrect or incomprehensible. What I am saying is your constructions stick out to me as something a non-native speaker would say or write, and that if I see much of that in written (or spoken) conversation, I do not consider the writer/speaker to be fluent in English. My bar for fluency may be higher than average (apparently even linguists can’t agree on a definition,) but it certainly is not common in the US to consider someone fluent in English based on the sort of limited proficiency that would allow someone to “talk somewhat freely” in English.