Genealogy /
Mosiondz/Mosiadz/Mosiedz surname [11]
My point was that none of these names are restricted to bearers of a single nationality. A name may be German or Polish or something else in etymological terms but is used in one form or another in neighbouring lands as well.
The word mosiądz is Polish, but a Ukrainian or Russian would spell it in Cyrillic Mosiondz, as the nasal vowel 'ą' does not exist in that alphabet.
Góra means hill or mountain, as does Berg in German and Yiddish. I'm sure you know that Yiddish is a dialect of German.
By and large it wasn't people taking on names, but others calling them by some nickname which eventually evolved into a surname. When there were many people named Józef in a given village, when describing their activities people had to tell them apart. So the bushy-moustachioed one became Józio Wąsacz, the blacksmith was Józek Kowal, Józio Dubiel, the clueless clumsy oaf -- Józio Ciemięga, Tom's boy Joe was Józwa Tomczyk, and Limpy Joe was Józio Kulej.
One example: a common German and Jewish name is Weiß. In a Polish-speaking area it could have got written down phonetically as Wajs, and when such a one emigrated to America, the Ellis Island folks, his employer or maybe he himself may have anglicised it to Wise, which of course completely changes its etymology. On the other hand if Wajs was aware of the etymology, he might have changed it to White.
But that's not all folks. It could have gone in a different direction. When Poland was independent, it may have been a better career move not to have a German/Yiddish-sounding name, so some people named Wajs would have translated it to Biały which in the Russian area would have been Byeliy and in Ukraine Biliy. In America, the Anglo-Saxon eye would have seen Bialy as Baily, and its bearer (so as not to have to explain things to everyone he met) might have gone along with it. But many generations away from a name's point of origin, it is often extremely difficult to track down its original form and nationality, especially since most people do not attach that much importance to family-name history and regard their surname as 'just another name'.
Hope this helps.