I think it's as simple as 'Ajokli speaks in bold font.'
Don't we get examples of Kellhus doing seemingly magically acts without sorcery before the speech starts to use bold font? I don't have the book in front of me at the moment to confirm one way or the other. If so that would suggest that Ajokli was in control of Kellhus before we start seeing the bold font. Also, if the Golden room is invisible to the gods, then how would Ajokli be able to posses Kellhus without being able to observe him? As the Dunsult note he could not be seen there by the gods normally. This isn't a problem if we assume he has possessed Kellhus before he enters the room. The only other option I see is that Kellhus would somehow have needed to switch his own head with Ajokli's after being in the room without anyone noticing or commenting. I have a hard time believing that given the amount of scrutiny he is likely receiving at that time, unless...some sort of magical chicanery that we aren't privy to is at play which is somewhat unsatisfying.
And as I mentioned in earlier post, the description of a 'descending hunger' sounds A LOT like how Ajokli has been portrayed so far (raiding the granary and all). The bold font hadn't started at that point and I very strongly suspect that was Ajokli talking.
I rule out Kellhus being on the Outside by the fact that Ajokli can not find him after the salting. If Kellhus was dead and on the Outside then Ajokli could see him and there is no reason for the Cnaiur possession. Even if we suppose Cnaiur was possessed by Gilgaol instead, then that still leaves the problem as to why he can't see Kellhus on the Outside.