Personally not a fan of the “voices”. The film offers a simple explanation: the spirits of the Sith live inside Palpatine, that’s it. It’s fine that this concept is only introduced in this film because it just builds on Palpatine’s character of pure evil, I wouldn’t want to overcomplicate things, it would be retroactively odd to never see or hear anything like that from Palpatine anywhere else before. Maybe it could work to replicate the raspy voice from ep. III as a callback(though I don’t think it’s necessary), but not anything as excessive as a legion of voices.

I don’t like the parallel to the Jedi voices, it basically puts them on equal ground, where I feel it works better to imply the Sith are essentially trapped inside Palpatine as a hive mind whereas the Jedi are free individuals who each have their own free will and literally stand on their own.

And there’s also the issue of muddling things even more, firstly with the opening scene where Palpatine speaks in the voices of Vader and Snoke, despite neither of them being part of the Sith conglomerate, and secondly with the whispering dagger, which I think should stand as it’s own separate dark side thing, and not imply Palpatine is literally guiding Rey around, specially since Hal has removed the “I never wanted you dead” angle and the film is already stuffed with “Palpatine was behind it all” elements. Just my two cents on the matter…