That was a pretty dense section, and I'm sure I don't understand everything that's going on. Some very good elucidation here. I'll try to add what I see:
1) One more thought on the "Zero God" idea: he first talks about "zero" as any point in space. There seemed to be an implication to me of, well, like imagine a graph from mathematics. (0,0) is the center. Each person is--potentially--the center, but only (as the Dunyain) if they can make themselves the measure of all things ("Submit to the rule of another and you will measure as he measures."). But Koringhus realizes that the existence of the God, the Absolute as something more than an ideal that they're reaching for: The God is, in fact, that zero point from which true judgement is passed, and it "had found his own measure wanting."
But then, several scenes later, as he reflects on the whole "Zero made One," which seems to be related to the love for his child that doesn't really fit into Dunyain culture, when he gets to this point, from Koringhus' perspective, "The Eye watches. Approves." He seems to believe that his "revelation" has been approved. If the JE approves, does this mean that he is, in this moment,
not damned? Is this--at least in his view--a redemptive moment? Does he kill himself because he believes he's not damned (which I suppose would be a good time to die)? If he kills himself because he knows his damnation... well, this seems like a strange choice. Sure, sure--there's despair, there's the qirri talking. But the fact of damnation seems to argue for either trying to find a way out of damnation or, at the very least, avoiding it as long as possible.
When we get the suicide itself, the text reads:
So quickly...
The events that transform us slip...
So quickly.
The face, cut into all expressions, all faces.
Eyes gazing wet from mutilation.
Fixed upon something that runs as he runs, a place he can only pursue, never reach...
Unless he leaps.
The Eye understood, even if the woman did not.
This is why I think he believes himself saved. He's been transformed, but he recognizes the very human difficulty of holding onto any transformation. As noted, it's a "leap of faith" that he's taking.