I also tried to call again the LOCTABLE_FROMFILE_GAME (C++) with a new path when the language of the game changes. First it throws an error because the stringtable already exists. So, I tried to call UnregisterStringTable before it. The error stopped, but it didn’t cause any effect and the texts didn’t update with new content.
It’s very frustrating not only because I don’t know how to do it, but also I don’t even know if I can do it. It would be so simple if the documentation only had a small text saying something like “You can load string tables from CSV files, however, you can’t localize it to multiple languages” or “You can load string tables from CSV files, and in case you want to have support for multiple languages, you should do this and that”.