There's a mod on the steam workshop that brings the values for the AI to form custom kingdoms and empires down to sane values, but I cant find it at the moment, I'll post when I do.Is there a way to lower the AI requirements for Empire? 120k prestige is insane.
I hope paradox fixes this however. Sure, the AI should be less likely to create a custom kingdom/empire, but it shouldn't be impossible as it effectively is now.