It happens when everyone around is a great writer and you just wanna keep getting more, it's a real struggle.
No worries about not knowing their canons, most of them will be only too happy to tell Irene about themselves a bit more if she's interested but otherwise their canon isn't all that important in the grand scheme of things. I bet the magic and stuff will be a trip for her, at least mine have all come from places where that's fairly normal so you know - it's not as much to take in for them.
Endgame was just a nightmare in a lot of ways for me, I'm still broken after seeing it, but Nebula, man I loved being able to get more of her and the interactions she had - they were just *air kiss*.
I'm excited to see Irene around, and see how she reacts to all the newness that surrounds her :D