Hello, I have got the same Problem, just installed the game but not on the drive. Also trough XBox gamepass and installed via the Xbox app.
My System language is German, I dont know what language the game is because <missing string nnn>.
The Option menu ist full of missing strings too, in fact the only thing I can read is the name. The displayed version of the game is V1.0.21.0000 LAX123ABCDEFGHI[TB]. The menu runs on 144 fps so thats fine (just mentioning because the [TB] part is speculative as my fps counter sits at the same place)
Edit: Fixed it myself by changing the LanguageName_h2027703280 Registry entry @Computer\HKEY_CURRENT_USER\Software\Obsidian Entertainment\Pillars of Eternity it was set on "german" and I changed it to "englisch" Funny thing is:
The game is in German now ^^
I hope this can help someone.
Cheers Neso