What I mean can be verified is that there are evidences from inscriptions or that the academic circles have already made a conclusion.
Speaking of verification, modern history, especially after the 19th century, I think such as old maps may be good first-hand information, you can directly see the location and writing of place names.
Cuneiform is more realistic than Aztec and Maya. Sumerian-Akkadian cuneiform has been encoded by unicode and has been supported. Other scripts such as Jurchen script have not been included in unicode, but encoding proposals have been made and are under review. However, the Aztec and Mayan scripts have not yet proposed a coding scheme.
For those bilingual place names that still existed before the British Occupation, it is obviously a bug that needs to be fixed, because they do not fill in the start date, and none of the place names can be permanent. However, these small place names may not be easy to find information to determine their start date, so they have not been corrected so far.
Tibetan, Mongolian, and Manchu can all be used as names, but there are still very few editors in OHM, so these places are only preliminary data, and many of them need to be corrected.
I understand that Koreans need Hangul to read directly, because it was the same when I edited Korea on OSM. But I think if both the editor and the web page can support displaying according to the user's language, then no matter what the name is filled in, it will not be an obstacle.

If the text used at the time is not understood by users today, I think the problem is that it can't be displayed according to the language the user is using, which shouldn't seem too difficult given that OHM uses vector rendering. OHM is not oriented to a certain country or a certain language, so it is the most neutral to use the characters used at the time as the name.
If it can be verified, there is nothing wrong with using cuneiform to write the name of the Sumerian civilization, otherwise there is no neutral language to write it.
The situation in Hong Kong and Macau is slightly different, although English and Portuguese are the official languages (Hong Kong added Chinese as the official language in 1970), Chinese is still widely used. A more similar situation is that the Chinese mainland released a simplified Chinese character scheme, we only use simplified Chinese characters after the release, and keep traditional Chinese characters before. Compared to Hangul which replaces Chinese characters in Korean, they are all the same language but written in different ways.

Historically, Chinese characters have been officially used on the Korean Peninsula. It was not until modern times (after 1948) that Chinese characters began to be removed. I understand that the hanja level of current Koreans is not good enough to read it, but please respect the historical writing.