Mimara's father was a Kidruhil, thus probably a Nansur noble and not a Norsirai. If Mimara is an Anasurimbor it's easy to explain why she has lighter skin, the Norsirai genes simply skipped a generation.

The whole No-God is soul-borne Nau-Cayuti... that literally is nerdanel in extreme - the only piece of evidence this is based on is that there is a nameless captive being dragged towards a Golden Room.

I don't buy it.

But equally nerdanel is the idea that Kellhus is time-warped Nau-Cayuti, which I do buy.

But hell, I've submitted that Achamian and Kellhus travel through time at the end of this series to fight the First Apocalypse.

While i do agree that there is no conclusive proof about Nau-Cayuti's fate, the nameless captive isn't the only indication that he ends up inside the No God. Aka's dreams in the last book seem to follow a logical sequence and most of them concern Nau-Cayuti. He even dreams about the manner of his "death" which was certainly not a part of Seswatha's memories. So it's not a far fetched conclusion that the broken man moving towards the Golden Room is in fact Nau-Cayuti. This also explains the Kelmonian prophesy, since Nau-Cayuti's soul would actually be present when his father died.

As for the Kellhus resemblance, why is it assumed that only one Nau-Cayuti's parents is an Anasurimbor? They were a very big family with allot of branches. And even if she wasn't an Anasurimbor she would most certainly be a Norsirai of the same era.  So he could look similar to Kellhus in Aka's eyes, and still be Seswatha's son that took after his mother.