The main problem with Luminous (and Zaladane to an extent) was that Marvel (and with Luminous I really mean Brevoort) was trying to use her as a "replacement" for Lorna as a sister to the twins. Not as another character that could add anything meaningful to dynamics among the whole family.
They were aware that fandom was really taking to seeing more of Lorna and Wanda interacting as sisters. The lack of respect for Lorna seen in her removal from a House of M portrait on Children's Crusade, exclusion from family moments in things like Axis and Avengers vs X-Men and Magneto: Not a Hero, etc, along with excuses at the time for why Lorna "couldn't" be Magneto's daughter, persisted in this too. Before Luminous, the attempt in Axis was to replace her with Enchantress. This was made fairly evident with things like this variant Axis cover that used color tweaking to make Enchantress look more like Lorna at the same time Marvel tried to keep ANXF #14 (where Lorna actually interacted with Wanda) under wraps.
If things were to be pursued with characters like Luminous and Zaladane, Marvel would first need to have it in mind to be respectful to all of the characters. If they can't do that, then using those characters is a mistake. It's just adding more problems that better people will have to clean up later (if they can).
I can also be reached on BlueSky and Tumblr. Avatar by kahlart.
Ghosts of Genosha minicomic focused on Polaris, written by me and drawn by Fin_NoMore.
Polaris 50th anniversary minicomic written by me and drawn by Mlad!
Gallery of Polaris commissions (without NSFW or minicomics)
Must have frequent guest appearances from Teddy and his family, Wonderman, Vision, Brother V, Viv, Victor, the YAs & Runaways
I’d love to see Magneto and Polaris in a team formed against the High Evolutionary, after they find out he is responsible for artificially erasing Scarlet Witch and Quicksilver family ties to them and also hiding the mutant nature of their powers.
THE BROTHERHOOD
-Magneto
-Polaris
-Scarlet Witch
-Quicksilver
-Mystique
-Toad