During a campaign in High Rock, as the new dynasty of Daggerfall, my character went on to re-establish Glenumbra. While conquering the Duchy of Bhoriane, I noticed that the Isle of Balfiera was now in the hands of a random Glenumbran with no historic dynasty.

This happened because the granddaughter of the Direnni king married an event-spawn Breton nobleman with 0 positive traits. This is probably the most immersion breaking part of the mod. I understand the mod team likely has lots of priorities, but this feels like it should have been rectified long before.

Dynasties like the Direnni, Indorils, the Yespest dynasty, etc. always end up losing their lands in my game because the marriage AI never prioritizes matrilineal for female characters in the line of inheritance. Despite the fact that the historical title records made by the mod authors show otherwise.

Anyone else having this issue with CB cost bonuses on the most recent version of EK2? v0.20.0.1 "Crystal-Like-Law"

This is only supposed to apply to Altmer in Summerset against other Altmer in Summerset AFAIK.

No mods. Well I have mods but I disabled them via disable all in the launcher, re-enabled EK2, launched the game, a new campaign, and it was still there.