On P4, Aya's bubble got a bit weird. I would suggest to change it to:
"I... Hmm, then I guess I am the "SMOOTH DELIVERY" type."
As for Maria - if this was animated, then the hair color would probably fluctuate... regarding your question, I think both have their own charm. I would probably leave the current one. The one here is nice, too... maybe add some more prominent and eerie violet strands and gloss into her hair, to make her aura even more dangerous.
Thanks for the chapter, it was hard work I presume and the result is really nice. And the clean images are appreciated