Apparently the decision to Restore Russia doesn't work. I took it as (the great-great-great-great grandchild of) a custom ruler ruling a Charlemagne DLC custom empire (created 4 rulers ago), Orthodox religion and Peterburzhets culture, taking the Cossack principalities as opposed to continuing to fight holy war after holy war against the now-united Communists. Any idea what the problem is?

We'll look into it.

Edit: We have fixed it and will update the mod when millero returns in a 1,5 week

Reforming a religion crashes the game

We've fixed that on our end, unfortunately millero, who can update the mod, will be gone until next weekend

The game always crashes on January 4th, 2527 no matter who i'm playing as or what I do.

Try reinstalling om Steam, of that does not work, use manual download. Remember to not use mods that are incompatible.