That said, the only book I put more work into was TDTCB, so your sense of haste actually has no basis on the composition side. I actually went through and rewrote the ending for 'clarity's sake' no less than four times (!!) based on feedback from different beta readers, which is what makes your appraisal of the 'general reaction,' to be honest, hard to believe. The Amazon and blog reviews don't reflect it.

Chapter 14 is pretty dense. I hoped to break down what happens to Koringhus tonight but I'm out of time. However, I've culled what I think the key passages are. I'll go through it all tomorrow hopefully. For now:

Some relevant points from the Encyclopedic Glossary:

Quote

Logos is the name used by Dûnyain to refer to instrumental reason. The Logos describes the course of action (so-called [Shortest Path])[1] that allows for the most efficient exploitation of one’s circumstances in order “to come before,” that is, to precede and master the passage of events

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"[the] darkness which comes before" -- A phrase used by the Dunyain to refer to the congenital blindness of individuals to the worldly causes that drive them, both historical and appetitive.

Quote

The whole point of the Dunyain ethos is to overcome these limitations and so become a self-moving soul -- to attain what they call the Absolute, or the Unconditioned Soul . . . The hope was that eventually [the Dunyain] would produce a soul utterly transparent to Logos, a soul capable of apprehending all the darknesses that come before.

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Among the Dunyain, [the Absolute is] the state of becoming "unconditioned," a perfect self-moving soul independent of "what comes before."

And a throwaway line that establishes that the Survivor is not to be trifled with. He appears to have been a Dunyain's Dunyain and so we shouldn't just dismiss his insights as the ramblings of a broken brain.

Quote from: pg. 391

He was known -- he who had confounded the Elders with his gifts.

And now to the disintegration of Koringhus' ethos:

Quote from: pg. 390

An absolute impossibility...

Referring to The Judging Eye. Koringhus realizes that the Judging Eye is wholly incompatible with Dunyain philosophy. Earlier in the chapter, when the Judging Eye first opens, he initially assumes the "certainty" that possesses Mimara is borne of madness because he cannot trace its Logos. Here, he's realizing it is neither madness nor sorcery.

Bakker italicizes "absolute" here because I think he's being cute with the language and making a double entendre. It's both shocking that Mimara knows about the stones, and specifically, it's impossible according to the Dunyain definition of "the Absolute."

Quote from: pg. 392-393

Only Cause could effect knowledge . . . "Cause measures the distance between things . . . This is why the strength of the Dunyain has always lain in grasping the Shortest Path..."

This is where his/the Dunyain's understanding of the world starts to crumble. Knowledge is supposed to proceed linearly, from The Darkness That Comes Before to conscious understanding.  However, he realizes that Mimara's knowledge of the hundred stones does not follow any causality or Logos at all. Her Judging Eye lets her sidestep Logos altogether -- for him, it's like finding out 1≠1. Everything he reasons in the rest of the chapter follows from this realization.

Quote from: pg. 396

The Dunyain, seeing only the skin of Cause . . . had assumed that Cause was everything, that it occupied the whole of darkness. But they had been fools, thinking that Darkness, even in this meagre aspect, could be seen.

Quote from: pg. 396 - 397

Pick any point in space - it does not matter which. The only way to make that point the measure of the surrounding space, the Dunyain had realized, was to call it zero, the absence of quantity that anchored the enumeration of all quantities. Zero... Zero was the source and centre of every infinity. And it was everywhere. Because Zero was everywhere, measure was everywhere - as arithmetic. Submit to the rule of another and you will measure as he measures. Zero was not simply nothing; it was also identity, for nothing is nothing but the absence of difference, and the absence of difference is nothing but the same . . . Thus the Survivor had begun calling this new principle Zero, for he distrusted the name the old Wizard had given it... God.

It's a little confusing without the italicized words but Koringhus here is realizing that The Judging Eye is analogous to the Dunyain understanding of the concept of "zero". The reason is that "Cause" are the little waypoints reaching forward into "Causes" and backwards into "Caused", if that makes sense. He uses the example of the boy's scabbed knuckles and notes that it was caused by something (maybe the kid scrapped it on something), and it will effect or cause something else (maybe the boy is irritated by the pain), which will be its own cause producing its own effect (the kid picks at it), et cetera et cetera.

And that this follows a linear progression. The Dunyain's entire project is producing individuals who can grasp a perfect understanding of these chains of cause & effect so that they can liberate themselves from them and become so-called "self moving souls". It's similar to Asimov's "psychohistory" from the Foundation series except at a much more granular level. The basis of the Dunyain's belief is the axiom that "Cause [is] everything"; that the whole of "the darkness that comes before" is undifferentiated Cause that humans are blind to and ignorant of.

So what's this Zero-God he invents? The next quote explains it a bit.

Quote from: pg. 397

The error of the Dunyain, he could see now, was to conceive the Absolute as something passive, to think it a vacancy, dumb and insensate, awaiting their generational arrival. The great error of the worldborn, he could see, was to conceive it as something active, to think it just another soul, a flattering caricature of their own souls. Thus the utility of Zero, something that was not, something that pinched all existence, every origin and destination, into a singular point, into One. Something that commanded all measure, not through arbitrary dispensations of force, but by virtue of structure... system... Logos.

As an aside, recall Kellhus' ministry to Proyas earlier in the book, where he gives lie to the worldborn conceit that the gods are in any way like men, and begins to refer to the God of Gods as "It":

Quote from: pg. 124

"... The infinite is impossible, Proyas, which is why Men are so prone to hide it behind reflections of themselves-to give the God beards and desires! To call it 'Him'!" . . . "This is the revelation. The God is not comfort. The God is not law or love or reason, nor any other instrument of our crippled finitude. The God has no voice, no design, no heart or intellect..." . . . "It is it . . . Unconditioned and absolute."

Emphasis mine.

The worldborn's mistake was in making sense of the Absolute by anthropomorphising it into a vaguely human-like God. Koringhus has appeared to grasp this same realization independent of Kellhus. The Dunyain's mistake, according to Koringus, was thinking that the 'Absolute' was a destination you could arrive at through intense training and evolving -- I don't think it's clear if Kellhus and Koringus are in agreement here, although I suspect yes because on page 123 Kellhus says that the God has no need of reason or Logos. There's a whole bunch else going on in Kellhus' teachings in Chapter Four that needs to be unpacked, though.

The point is that both were wrong. It is not a destination and it is not an origin. It is both and neither at the same time; a singularity. It is "One."

Anyway, the Judging Eye shows that there can be knowledge without Cause; knowledge without distance. Nevermind following the Shortest Path, for some there are apparently no paths at all. Later on, he'll call this the "sideways step that [gives] lie to Logos."

To break it down more:
Cause = the distance between things (cause & effect);
Zero = a singularity of cause & effect; a point where cause and effect are undifferentiated; a point where everything is One.

I think at some point off page, I think Achamian must have conflated the Judging Eye with God. The Survivor distrusts that term for whatever reason, so he instead refers to the principle underlying the Judging Eye as the "Zero-God".

The Absolute = Zero = the Zero-God.

Ajencis' Dyadic Principle ties in to this somehow but I don't feel like unpacking it at the moment. In short, Ajencis claims that "it is the relation between subject and object, desire and reality, that underwrites the structure of existence," and the "many regions of the Outside then represent diminishing levels of objectivity, where circumstances yield more and more to desire." If you think of Desire and Circumstance as Cause and Effect then you can start to infer that maybe the problem with The World is precisely that the Zero-God cannot (for whatever reason) incorporate it into its Zero-ness; it can't close the gap between cause and effect. But why?

Quote from: pg. 397

The God that was Nature. The God that every soul could be, if only for the span of a single insight... The Zero-God. The absence that was the cubit of all creation. The Principle that watched through Mimara's eyes...

I'm still trying to parse what the bolded part might mean.

Between this and the next quote, he snorts the Qirri.

Quote from: pg. 403

Thoughts, like legs, were joined at the hip. No matter how innumerable the tracks, no matter how crazed or inventive the soul, only what could be conceived could be seen. Logos, they had called it, the principle that bound step to step, that yoked what would be aimless to the scruple of some determinate destination. And this had been the greatest of the Dunyain's follies, the slavish compliance to reason, for this was what had shackled them to the abject ignorance of their forefathers... Logos.

Quote from: pg. 407

Only now did he understand. Ignorance. Only ignorance had sealed the interval between [himself and his son]. Only blindness, the wilful idiocy that was worldborn love . . . He clutched this wailing burden to his breast [his son], this impediment, without thought, as if it were no less a fraction of his own soul, a part that had wandered... Zero. The difference that is not a difference. Zero made One.

Quote from: pg. 407

And so it was with the Absolute ... At last he could see it -- the sideways step that gave lie to Logos. Zero. Zero made One.