Have we ever gotten any info on what exactly goes on in the Cognitive Realm on Sel other than that its extremely dangerous because there is a lot of "mindless" Investiture around? We know Hoid has made a trip to Sel, presumably through the CR, so it must be possible to survive there. So, if that is indeed the Hoed from Elantris, he either got rescued or somehow figured out how to survive, I guess.
I'm referencing this WoB: