@Lumnor
My priority right now is to add more beneficial events. I think that I've added a bit too many ways to turn your ruler into a wreck, so I need to balance that a bit. If by histories you mean adding new historical characters in, then linking them to titles and between them etc etc, well I'll be honest I might never do that - it requires a huge time investment and I am not sure I ever want to commit that time to that. I've already dedicated an enormous amount of time to this mod as is.

If someone has a passion for that and wants to help, I'm willing to give them some creative guidelines and be lenient on their work to fill some stuff... But me? At most I would add a few random characters to titles and call them the names required so some select characters like Shapur are not no. I.
What I would want to do is add a few select "histories" or "biographies" you can read via tooltip in game. Not sure how to implement those yet, I'd basicaly like to give a small history of some dinasties or locations / states - maybe even religions for those who have no clue what they're about.
@Bad_Haggis
I was thinking of implementing a celtic empire, but I'll think of that one too. Looking into implementing an empire in that area now, will get back to you once I do.
I've added a Celtic Empire - requires you to be Irish/Brython/Scottish/Welsh/Breton/Norsegael/Galatian. You need to be King of Alba and Hibernia, and directly control Nantes, Dumnonia and Gwynned. I'm unsure what to call it exactly...any ideas?