Personalization is inherently selfish. Take osm.org’s layer switcher for example: each layer exercises some editorial control over which subset of OSM data to show. Yes, a map in the user’s language ignores the herculean efforts that have gone into coverage of other languages, including my own. Americana is not the first map to commit this sin and it won’t be the last.
Yet a map that adds the local-language names in parentheses is attempting to strike a compromise, reminding the user that not all the world speaks the user’s language. I shudder at the thought of an American tourist landing in a foreign country and expecting everyone to speak English. Labeling a city in the local language can help prevent that situation, but first the user has to be able to find the city with the language skills they have.
For those who prefer to see as many languages as possible on the map, there’s a “multilingual” mode that uses the name tag by itself, without any name:* tag.
(Oh no, Pascal strings…)
Judging from the screenshot, I think you’re suggesting that the renderer iterate over all the name:* tags (ignoring things like name:etymology and name:genitive), looking for substring matches within name. That’s essentially what Tracestrack is doing, but it’s too simplistic. You got lucky that “Cottbus” isn’t part of “Chóśebuz” or vice versa. For better or worse, this method would be much more reliable if the names were separated by something that can’t occur within a name.