I’m going to talk about Luminous. This is going to be a quick, simple opinion, one others may not agree with.
The problem with Luminous isn’t that she exists. The problem with Luminous is her reason for existing.
I’m a firm believer that no character is truly terrible and irredeemable. Characters can be used well or poorly, they can be written spot on or completely out of character, but there’s always something about them that can be good.
Fans of Wanda, Pietro and everything tied to them know what’s wrong with Luminous, even if they don’t quite know how to vocalize it. They know why she exists. They know what function Disney and Marvel jointly want her to serve. Luminous has no future as long as the things Marvel changed that led to her creation remain as they are.
Undo the retcon forced on Wanda and Pietro during Axis. That is the only real option for Luminous if she is to have any kind of a future ahead of her. This is my one olive branch of advice on this matter, and I give it because I want to believe there’s a desire to see Luminous last and be perceived as having some semblance of worth as a character. I hope my trust is not misplaced.