I think that stuff like "polish army" is a bit too generic and proper original names should be used if known (with a translation of course), as putting the actual name of the users only on English and American masks is too anglocentric
This is an English-language wiki, so with respect to language it's necessarily anglocentric. Unless the name of something in a foreign language is pertinent, or genuinely useful for disambiguation, it seems rather out of scope
Even though this is an English-language wiki, the idea behind it is to make it international. If there is not a specific universal translation in English for one term (i.e. "Germany" is universal, "Polish army" is not), there should be both the proper name and the translation. At least, if the proper name is provided, it shouldn't be deleted.
"'Germany'" is not universal at all. In German it's "Deutschland", in French "Allemagne", in Polish it's "Niemcy", In Japanese 「ドイツ」("doitsu").
Despite this, we do not refer to the name of a country in the language of the country in question because it's not relevant, and the same is true here.
If an unambiguous translation is possible, then it's moot. A Polish person who speaks English reading the article should understand "Polish armed forces" just as well as they would the Polish equivalent.
In addition, the use of languages is likely to force infobox entries onto two lines where this may prove unnecessary, where the height of infoboxes already presents formatting issues
This wiki is principally an English language wiki, so it's my view that other languages should only be invoked for the benefit of the English text (i.e. where it's relevant and where a translation is provided)