Personal unions

I got into an extremely frustrating bugged situation involving the golden horde somehow ending up as part of a personal union with myself (Muscovy), Kiev, and Lithuania.

I think Kiev declared a war to claim the throne of the horde? Don’t ask me how, I couldn’t tell you.

As a result, my ruler and heirs kept being assassinated due to what I believe was a horde civil war disaster ongoing in the GH. I checked, and no, the GH doesn’t actually have a spy network on me. Parallel to this, my ruler also kept converting to Sunni (don’t ask me how, or why, the game conveniently never informed me about any of this, since the GH is getting the events. Nor do I have a button to make the idiot change his mind.).

This kept causing issues with religion of the heir laws in Lithuania, which required me to use negotiate succession. Which I had to then use multiple times, since they also keep changing that law, or something else.

Eventually, due to what I can only assume is related to the fact that my ruler was forcibly Islamized, Lithuania was left with no selected heir religion law, and was refusing to select any. This seems to cause none of my heirs to be valid, since the default state of a personal union religion inheritance is same religion, even if the “same religion” law isn’t actually passed.

The only way to keep my union with Lithuania was to…tag switch to them and force them to pass a law they were sitting on for at least 6 years.

This makes it so, inevitably, the union collapses in one way or another, and all of my integration progress is inevitably reset, even with Kiev, who has been sitting there loyally for like 20 years.

My question is : why? Why is there absolutely zero feedback about any of this? Why give players the ability to form unions if they are so incredibly brittle? Also : How the hell did the Great Horde (a Sunni country) join my orthodox union?

Can we just make personal unions back into a special subject type? Or otherwise have a way to more strictly enforce or control their laws and policies? Can integration level of the union partner be some sort of decaying modifier, that increases over time rather than an arbitrary gate that gets slammed shut if, god forbid, anything goes wrong with your succession, ruler religion, heir religion, culture, the fucking wind direction, etc? This would make situations where there’s inevitable union changes (such as dynasty changing due to female heirs) much less punishing?

I get that personal unions are supposed to be messy, but they feel fundamentally unfinished as a mechanic. Can’t wait to get the 15 dollar DLC that makes “claim throne” a useful CB.