OS Mojave 10.14.5 stuck after changing language

since 2 days my MacBook is stuck on boot after changing language in the systems control panel: Before the login I just see a circular loading indicator and my mouse cursor is stuck in the top left corner.

It seems like a service is restarting all the time since the loading indicator spins for like 10 seconds before disappearing and reappearing again.

I tried resetting the NVRAM, first aid from the disk utility and reinstalling OS X – it all fails and so I’m still stuck. I also tried running languagesetup from the single user shell but this just returns an error message saying “file or folder not found”.

Im running OS Mojave 10.14.5

Hoping someone has some advice since Im fearing only formatting can rescue my MacBook.