So from the mapper point of view, a mapper who knows the city is called Beijing in English can no longer tag that? They would have to know what language it originated from, and understand the more complex tagging. And the same for mappers tagging exonyms in all other languages.
And from the data user point of view: maps rendering names in English would be broken in the short term. They would need to search for all tags of the form name:en-something. And if there is more than one they would have to break the tie somehow.
Have I got that right? It seems like a lot of disruption even where there are no politcal complications