Haha, man, I feel like the most stupid person on this side of the planet
You know what the problem was? I had my bash installer priority UPSIDE DOWN. And I thought it was supposed to be that way (wasn't using WB for about 6 years now). I thought Priority 1 meant first priority, and the "Last" marker meant, a mod that overwrites all previous.
I feel very stupid. I guess the time using Mod Organizer has somewhat deleted all my former insights...
I will now rearrange my installers load order and that should fix it. Funny enough, that I didn't encounter any other issue in my game (12 hours game time) other than this.
Thanks for your time though, I was really not able to figure this out, without somebody else having a look at it!