I like the ideas. Granted, it does give Kylo less of a reason to reforge his mask which Ascendant fixes pretty well. Then again, I never had much of an issue with that to begin with. I’d be curious to see what else you can come up with here.
Sure, Ascendant gives us flashbacks to ‘a creature in a mask’, but I don’t think that is a reason for Kylo to reforge it. If anything, I’d think Kylo would want to connect with Rey without the mask to interfere, so that Rey would view him as more of a person.
I think the most coherent reason for the reforging (other than rule of cool) is simply that he’s ‘serving another master’ but with an ulterior motive, so the helmet would mask his expressions while also visually signifying that he’s taking the role of Vader in Palpatine’s orbit. I don’t think we can get a deeper character reason, so to go from meeting Palpatine to the mask reforging would strengthen that concept.