I really can't follow you that far, sorry. While those are all possible explanations, I think the more common explanation offered for those events are more parsimonious.
I do have one huge reservation about what you seem to be suggesting RE: Kellhus and Moenghus using the Psukhe on him. It's implied a few times in the books that the Cants of Compulsion do permanent damage whenever they're used, and even while the Cant is still working you're somehow lesser than you were before, they break you in some way, and make you never whole again. Xinemus's continuing derangement is evidence of this. It's not just due to the trauma of being made to mean what you do, of not knowing where you end and the other begins. Something breaks in you afterwards. Perhaps something in your soul, since that's what's being directly brutalized. Achamian thinks about this when he considers using the Cants on Inrau. I think to use the Cants of Compulsion on a Dunyain would be to take away all the advantages of having a Dunyain on your side in the first place.
Also why wouldn't he just implant the goal "Shimeh...I must
serve my father in Shimeh" and thereby avoid embarassing situations like Kellhus bringing people to kill him instead of aiding him?
Incidentally Esmenet is either extraordinarily strong-willed given how few ill-effects she experienced after Aurang used the Cants on her, or something about the Cants of Compulsion Aurang uses are fundamentally different. I suspect the latter. In no other instance do the Cants demonstrate the effect on those they're used upon that Aurang's did on Esmenet. In all other instances, the Cants make the victim simply come to the conclusion that what you said was true and what you wanted them to do was right, all the while feeling that it was of their own free will. And there's elements of that with Esmenet. But Esmenet isn't just
compelled by Aurang, she's possessed by him. Utterly consumed by him. Her own identity vanishes entirely, and Esmenet becomes little more than another body for Aurang to inhabit, like the Synthese.
I don't think during Akka's interrogation that Xinemus
becomes Eleazaras at any point. This is something different. Perhaps another hint that this is a whole other level of sorcery is that the flow of information actually went both ways this time, with Esmenet getting some fleeting impressions and memories that in fact belonged to Aurang.
So basically I challenge that Aurang simply used the traditional Gnostic Cant of Compulsion on Esmi.
"His surroundings INHABITED him, POSSESSED him, until he was moved by all things at once"
So Moenghus is using the Psukhe on unsuspecting Kellhus. Bakker hints at it with "inhabited" the same word Kellhus used to describe Moenghus' relationship to Cnaiur to...uh...Cnaiur.
Two things
1. I don't think this is a hint from Bakker because the entire reason Kellhus used the word "possessed" when speaking to Cnaiur that time was because he could see the word forming in Cnaiur's mind and wanted to gain leverage by confirming to Cnaiur what Cnaiur wanted to believe (That Cnaiur bore no responsibility for his father's murder, was merely an instrument of someone else and so could not be a murderer by definition)
2. The relationship is irrelevant anyway because Moenghus never needed to use the Psukhe to "inhabit" Cnaiur. Which he couldn't have anyway, since he hadn't learned it yet.
Further down the page we see the Psukhe reducing Kellhus into a tabula rasa
"Like a sheet of parchment exposed to the elements, each day saw more words stolen from him--until only one imperative remained: Shimeh...I must find my father in Shimeh"
I actually think this is a deliberate echo of Kellhus' whelming in the flashback later in the book, with the phrase "The Logos is without beginning or end." replaced with "Shimeh".
What's reducing him to a tabula rasa is his inability to cope with a world where thousands of new stimuli occur at once after living 30 years of his life in a place where absolutely everything, down to the falling of leaves, was premeditated. He's experiencing sensory overload, and shutting down to compensate.
"His disPOSSESSION deepened, until he no longer slept or ate."
Again, this is a second Whelming for Kellhus, analogous to the growing disconnect between his mind and his body as he endlessly repeats the proposition in his mind, soiling himself and barely noticing, certainly not caring. Just repeating the proposition.
Further down the page, more hint
"If the wilderness could not POSSESS him, it would kill him."
The Wilderness in this second Whelming is analogous to the Legion Within in his first Whelming. The whelming is almost done and the constant tugging of the thousand variables (like the constant beseeching, almost heard voices of his unacknowledged thoughts and feelings in the Whelming) are becoming desperate to drag him down.
Kellhus is all better at Leweth's making the time between leaving Ishual and being found by the trapper the most personally tumultuous time for Kellhus until the Circumfix.
...and his hardest trial since his Whelming. (though I'd argue the Circumfixion was his third Whelming. Kellhus is reborn as a person after each one, and each marks a significant departure from who he was before:
1st Whelming: His Whelming with the Pragma. Begins as a child under the sway of the Legion. The child dies and is reborn a Dunyain Monk, one of the conditioned.
2nd Whelming: Begins as a Dunyain Monk, incapable of letting a single variable slip past his notice even when he wants too, though the constant stimuli nearly drives him mad and kills him, or reduces him to the state of an animal. The Monk dies and Kellhus becomes a his father's son, a Dunyain of the World, able to ignore through the howling of the legion of uncertainties and unerringly find the shortest path, now concerned only with the mission.
3rd Whelming: The Circumfixion. The Dunyain son of Anasurimbor Moenghus dies, and Kellhus the Prophet/God is born. This is when he stops being Dunyain entirely, and becomes something More. (or something Less. It remains to be seen.)
Aspect Emperor Spoilers
It's possible that if he's changed significantly in Aspect Emperor since the end of Thousandfold Thought, that his trip to the Outside was a fourth Whelming.
Of course the Circumfix is also all psukhe-conducted. The Cishaurim are there, they make voices for Cnaiur to hear but no one else, they give Kellhus dreams, mold his soul, they make it possible for him to pull out his own heart, survive, and leave no mark.
That's a lot of big jumps of logic and assumptions about the abilities of the Cishaurim. Is it not simpler, requiring less assumptions to simply believe that even a Dunyain body can only deal with so much stress, pain, dehydration, and sleep deprivation before it begins to hallucinate? Or he's actually Divine and talks to the No-God or something, I guess. I don't favor that view but suit yourself.
And really, if Moenghus controlled and calculated this much of Kellhus' journey, how did he wind up getting himself killed and totally misjudging Kellhus' motives? Especially if he had invisible Cishaurim following him around all the time.
Another hint? P. 11
"Leweth would watch from across the fire, his hands living an ARCANE life of their own"
To a Dunyain fresh out of the monastery, anything to do with rituals or Gods is the same thing as sorcery. And sorcery is just bullshit and superstition. This is what is meant by "Arcane".Leweth's hands are animated about the tasks of magic thinking.
Leweth, the carefully chosen (crafted?) template, the lense through which Kellhus sees all other world-born. Maybe Leweth is Ultra-Dunyain, able to fool even Kellhus with appearances?
If that's the case then Moenghus had a hell of a powerful agent turned into Sranc fodder on the ass end of the Old North.