What about Monachium, Norymberga, Kolonia, Rzym, Padwa, Praga, Paryż? Do you get my point? Muenchen is Mnichov in Czech, by the way.
What about Naples in Italy? For Italians it's Napoli, for Poles - Neapol. Rome? For Italians - Roma, for Poles - Rzym, e.g. for Russians - Rim (Рим). Cities, especially big ones, have different names in different languages - like countries. Usually the differences are small, but for example Polish name of Italy is Włochy, on the other hand Hungarian name of Poland is Lengyelország. Interesting is Montenegro with its Polish name - Czarnogóra. Taking cities again into consideration - popular Polish transcription of Pyongyang is Phenian (but Pyongyang is also in use), often pronounced in English style.
In Poland we say Monachium for Muenchen, Germans say Stettin for Szczecin or Danzig for Gdańsk. Ukrainians have Lviv (Львів), we say Lwów. Szczecin and Lwów can be explained by that before World War II Szczecin was a German city, Lwów was Polish.
I can understand ignoring Polish letters abroad (especially in texts typed on computers - though Polish is quite comfortable here, we don't have different keyboard like Germans, the only thing to do is to change keyboard layout in settings and to know how to use Alt key to type Polish letters), but what I sometimes meet and can't understand is ignoring them in pronunciation.