In terms of Jean and Magneto; she's never seen it for him. She's only ever interacted with him in the context of him being a villian that tried to harm her and her friends multiple times as she was never around when he was an X-man. That all changed a few years ago when she came to present day as a teen and he mentored her much like Xavier did. She has those memories and has seen the humanity within him and knows he has the capacity for good and truly does mean well for mutants despite the previous lens she had of him growing up. This new context can account for the change she has in terms of being open to him. Additionally everyone she trusts likely vouches for him. Xavier, Scott, Storm, Kitty, Rogue, Logan, etc... Magneto has more than earned his respect
In terms of Krakoa, the stuff she was doing in Red is a predecessor to this on a much grander scale. I dont think she would be opposed to the idea. Maybe the implementation but just before HOX, the world went to sh-t when it came to mutant-human relations. Disassembled is enough justification for why any mutant would at least entertain something different