Hmm think corruptor and I assume purifier are quite weak. I understand that eye color, sclera color, and pupil shape are there to delute pool but to be honest, removing those at least from critical results, instead of +1 change would be better. Because to be honest those classes not really useful even if you prepare soul for one of sales. (pretty tricky I like that assignment.) but more often than not you can get critical change (eye pupil square/ eye pupil triangle) and that or eye color.
I feel like either getting few demon covens (think archtypes) if just letting corrutor try to get to certain mold feels too weak. Can even pick those based on corruptor and target picking those or assigning them to random based on what ID soul happens to be. And making corruptor work to those would work better. Because I dunno only thing I find them of use the to corrupt someone completely and then body swap a twinner into it and use that way if twinner actually does not do the same thing.
Even corrupt angel task, which should be their professional thing, you end up with better results just letting your usual team work normally even if due to negative traits things get far less likely. Maybe just after that leave for a few turns for corruptor to work and hopefully add trait or two that benefit.
Edit: or maybe instead letting them implant corruption shards into soul. Like minor curses that change certain perks over time.(or make them equip on soul such item.) I feel there are many things to make them interesting. At least in areas where normal hypnotist or mind writer is useless. (yeah there are still demonic transformaitons which body shaper can't do with human souls, but I feel it corruptor is a bit useless.) Maybe same with purifier.