Acadia maintained her powers as a ghost so one could argue even there brain might not affect. There powers, if anything horns would be like, focusers, make it easier but if they were damaged they would just need time to adapt

I mean there’s also a theory that Aradia was able to keep being a Ghost and doing stuff for so long because her Dream Self was communing with her Soul while it slept in Derse. When the Bubbles aren’t involved, Death in Homestuck sure is weird!