The trade offs sound great - like casting a spell in Call of Cthulhu there should always be a cost (in that case SAN or POW) for using supernatural abilities in a horror game, I reckon.
I like Curse of Strahd for the most part, but the Vestiges are Dark Powers definitely got removed from my play of it! Lost the best part of the original setting for me, the way the land itself corrupts. I gave it my best stab at giving them dark gifts as their actions warranted it but home brewing it in 5e was a challenge, especially in a way that felt like it grew as they did worse things.
Liking the sound of Fortune too. I think for Gothic horror the element of morality is really important and having an easy to implement system to support that would be really helpful.