I will try to make a more serious post, attempting to explain parts of my reasoning. I will also try to separate what i actually think is probable from the crackpot theories i do for fun.
I've believed (and probably stated here or in the asofai forum) that Mimara was a true Anasurimbur since the moment i put down the JE for the first time. This came before

. The Nau-Cayuti part was seeded by Scott's comment about the timing of the dreams. Why had Aka to learn now about Nau-Cayuti? He seems to follow his story from conception to "death", breaking every rule about the dreams in the process. It's not about the Heron spear, the narrative surpasses that point and goes on to place him in Golgoterath at the end of his life. And while we don't know why it took the Consult/Inchies so long to build the No God the first time, the second time should be faster. They have the know how, the carapace and no one believes they exist. They seem to be waiting for something.
All this (with the exception of Mimara) is not speculation, it's taken directly from the books. I tried to connect the pieces we have and Nau-Cayuti seemed to me the most probable common factor, as implied by the dreams. I am still working on my Elvis theory, when i am done i will post it as another atrocious tale (hopefully even more badly written than the first one). For now, the only connection i can see to all this is Nau-Cayuti.
The No God theory started to form in my head when i was reading the first trilogy. There was a lot of talk about the outside, where souls went to be judged. But to me, the most important clue was the negation in the name. I mean there had to be a link to the outside, but we didn't know enough about the Gods so i didn't have anything solid to apply that negation to, which led to a lot of head banging against the wall.
In the second trilogy we are given the information that the God is the sum of all souls. If this information is correct the form of God includes an inside, the physical world, and an outside, the metaphysical/conceptual world. Let's apply a negation to that. The No God, must have a conceptual world inside, and a physical world outside. Indeed the outside of the No God, the carapace has a physical form and interacts with the physical world. This is of course just a guess, but an educated one, i tried to use the clues we are given and combine them with the least amount of complexity.
If the God is the sum of everything, then every soul is not really new. According to the principle of energy conservation the parts that form the entity that is God should always produce the same sum. So souls are in a way recycled through the death and rebirth process. Following this logic, and factoring that according to various characters in the books souls aren't equal, a more important soul represents a bigger part of God. This view is also expressed in the books, so i think it is more or less correct.
The logical leap is that if you want to change the way God works, you have to subvert an important part of him. The number of souls is a factor, but so is the density. Thus, creating the No God using souls makes sense and a soul like Nau-Cayuti's should be considered a prize. Since he was actually there at Golgoterath at that time, it's not
that far fetched to assume he was indeed used to that effect.
I've also toyed with the idea that the No God is a trap for the ciphrang (including the hundred) and that's why there are no new births, Yatwer has left the building. Maybe they used an important quantity of souls to draw the hundred in its mini outside and trap them there, negating damnation.
In any case, if God's outside is closed to the world, Nau-Cayuti can't be there. So he has to be somewhere else. It's not such a big of a leap to assume he is inside the No God. The timing fits, but there is a problem as you've pointed out:
The Celmomian prophesy doesn't make sense. We are constantly reminded that when the No God walks the earth, the outside is closed to the world. The Gods are part of the outside, so they shouldn't be able to communicate with Celmomas. This is supported by Maithanet's notion that they can't see the No God. Since the Gods experience all timespace constantly, they don't have access to that specific part of it, so how could the have agency at that time? In the AE, the only God that seems aware of the No God is Ajokli and that's an other inexplicable exception that doesn't fit with anything else we know. The rest of the Gods that have agency in the AE's present, act like they don't know about the No God. So the clues we are given are conflicting with each other, making an accurate prediction impossible. Someone lies, that's for certain.
There is also the matter of the source of the prophesy. Seswatha, if it actually is
his heart that the mandate uses for the dreams is completely unreliable. We just can't take his purpose at face value, not with damnation hanging above his neck like an axe. It's interesting to note that real or not, the Seswatha whose heart seeds the dreams has in this way become immortal, avoiding damnation. I don't believe in coincidences

. On the other hand, the Consult seems to also follow a prophesy. The only common factor i can see between the Consult and the Mandate is they both believe there is
a prophesy about
a person when the world ends. They obviously disagree about who that person actually is, but this common factor seems to indicate that somewhere down the line there is a single origin.
I also believe the baby is important for reasons i've already explained. He might be the harbinger, he might be Nau-Cayuti reborn, he might be something else entirely, i don't really know. The only thing i am certain of is that he is connected to the second apocalypse.
The rest is just for fun, an attempt to bridge the above with the fact that events repeat themselves in Earwa. there is little point in attempting to debunk or confirm them, because at this time we know jack shit

. That's why the conversation becomes cyclical. Scott has given us five books full of clues, and we can trust not a word of them.
So if i say that the story is about the God, trying to understand itself, i am not searching for evidence. It's just a baseless opinion. I am sharing it because i think it's interesting, not because it's necessarily true.