While entering the addresses for the hospitals in Mae Sot I stumbled over this. I used tags like addr:street, addr:city, etc. to enter Latin names. Perhaps I should have entered the Thai names here, but how do I tag the other lot then? addr:en:city=* ? This doesn’t appear documented anywhere.
Since I don’t read or write Thai for now I have created a tag addr:th and pasted what looked like a complete address in.
I’m not sure about the preferred method, but Nominatim currently seems to work whatever language you use, i.e. it will match the addr:street tag with any name:language tag the street has.