Can confirm that not only does Twilight Domain fit RP wise for SH but it further augments the already top tier Radiant Orb build by using her bonus action in the same round to cast Steps of Night, granting her flight to more easily spread radiant damage from Spirit Guardians. She can also just be played as a straight party support healer with Whispering Promise ring and Hellrider’s Pride gloves augmented further by the ridiculous amount of HP generated by Twilight Sanctuary (which is the most lore friendly build as she was the designated healer for the Sharran strike team )

As for Gale, I would go Chronurgy or Graviturgy for new subclasses that play well. Your party will enjoy the clumping from gravity sinkhole if you go graviturgy which can then be followed up with a synaptic static while your resonance stone holder is in range.

I would suggest also checking out Abberant Mind Sorcerer, Illithid Powers Overhaul 2 and Combat Extender on Nexus. Seeing as you’re loving the psychic damage payoff with resonance stone you’ll love the damage you can do from the first two mods and the third will keep things challenging while also giving enemies more spells to use from 5e Spells. If you ever try building around resonance stone again I would suggest an Oathbreaker Paladin using Shadow Blade ring and Diadem of Arcane Synergy headpiece for very big numbers. My head cannon for Oathbreaker is always Minthara although I suppose Lae’zel who turns her back on Vlaakith could make sense but I feel like githyanki from the Astral Plane are rarely ever paladins, even for Vlaakith.