Glad you managed to publish your query, but it may also be worth posting it in one of modding community help sections of Larian’s Discord. Modders tend to hang out there more than here.
I’m also going to just move this to the modding subforum, where it’s more likely to be seen by someone who can advise.
I managed to play BG3 in Dutch, although I have to say it didn't go as I thought.
Normally you create a MOD, place it in the MOD folder and use your MOD manager to manage and activate it.
Now I made a backup of the "English.pak" file in /data/Localization,
Unpak English.pak
Translate English.loca.xml
then created a new "English.pak" file with the translated "English.loca.xml" file and overwrote the original "English.pak" .
I don't know whether it will have negative consequences later, for example if a new patch is launched, but it works fine.
