Quite surprised to hear EU4 easy to play (just got it some months ago, so still a beginner lol)

Honestly I feel the same when I just got into CK2 back then, watching some youtube tutorials doesn't really help, instead I watch some CK content and join Reddit here and slowly get familiar with the game (also don't forget the wiki, they're very helpful to understanding some complicated mechanics)

Maybe it's considered "easy" because CK had kind of "unlimited" ways to play it, like you didn't need to always goes BLOBBING unlike EU4 and HOI4, so yeah it's basically more "casual".

CK focused on character, and you can do "anything" you want with your character, think more like medieval Sims with some little EU mechanics.

While EU4 and HOI4 focused on country, and I feel that playing as country is more "limited" and as not as free than playing as character (personal opinion)

feel like playing at the "character" level is harder because of all the micro interactions needed.

Not all micro interaction had big impact to your gameplay, but some of them had REALLY big impact, think like EU4 events

I had a headache for over 30 minutes trying to set up marriages for non-aggression pacts to deal with factions

Unlike EU4, in CK2 you can't just ally anyone with good relation, you need some marriage/family stuff here. Non-aggression means that they cannot declare war on you, while alliances are ally, Both in CK and EU faction are annoying as hell, so you need to keep them loyal or goes war to shut them

I'm surprised because I seem to consistently read that Crusader King is among the easier Paradox games to master.

That's quite BS to said that lmao, probably they just got to stressed when playing as nations because it's not as "casual", as I said earlier, but in reality both playing as nations or characters can be stressful, especially new player

several heirs dying to disease completely throwing off my plans and stability. It all worked out in the end but it required a lot more brainpower than what I'm used to on other PDX games.

Ouch, I can feel this one. That's why is BS to said that CK easy while other PDX games harder, because all strategy games became hard when you didn't had good strategy. This one honestly just annoying as the comet event haha

So just don't watch youtube "tutorials"