Do you write Iulius Caesar or Julius Caesar? Same writing system (or rather, it even originated there).
Generally, even without the counterexample, you just postulated an arbitrary, somewhat contrived rule. "Cities can have different names, people cannot, but only as long as the writing system matches". You can want this, but good luck with getting language to adhere to it.
If I'd correct Germans for all their "misuse", or at least idiosyncratic use, of English expressions (handy, public viewing, "learnings"...), it wouldn't make anybody happy. I put "misuse" in quotes deliberately, because German has just adopted these words into different meanings and connotations, just like Japanese did, and that's okay.
Generally, even without the counterexample, you just postulated an arbitrary, somewhat contrived rule. "Cities can have different names, people cannot, but only as long as the writing system matches". You can want this, but good luck with getting language to adhere to it.
If I'd correct Germans for all their "misuse", or at least idiosyncratic use, of English expressions (handy, public viewing, "learnings"...), it wouldn't make anybody happy. I put "misuse" in quotes deliberately, because German has just adopted these words into different meanings and connotations, just like Japanese did, and that's okay.
Language prescriptionism is not realistic.