When grimdark Rose came back as a ghost, wasn't she no longer supposed to be grimdark? Also, why didn't Aranea's GO! Self become a ghost?

The artist who drew grimdark Rose as a ghost said it was a mistake and that Rose was supposed to revert back to normal. As for Aranea’s GO! self not becoming a ghost, it may have been that Hussie just decided not to show her. We weren’t able to see GO! Karkat or Kanaya either.