As you weren't reading the XoS in it's entirety might I suggest watching Youtuber Wildebeard. I've been followin him for quite some time now and he gives really solid, objective summaries on the books he reviews. I was able to follow quite easily the XoS chapters I wasn't picking up.
Lord Ewing *Praise His name! Uplift Him in song!* Your divine works will be remembered and glorified in worship for all eternity. Amen!
Arrako is basically the bulk of the mutant population of Earth now. They've basically been living Age Of X for centuries and are not used to sharing a world peacefully, so a lot hinges on the Krakoans getting the Arrakii to co-exist nicely with base humanity. Having all these extra mutants around could help an awful lot with Moira achieving a future where mutants don't lose, but if they precipitate a war with humanity they could cause a bad outcome instead.
I'm super intrigued by the Arakki mutant nation. But I'm also afraid it will take 2 years before we really revisit and get to know them. Hickman's writing is so overcrowded with ideas and some other plotthreats seem to be coming first.