The thing is the information in the appendix is taken from the Isûphiryas of which just one copy was given to men by Nonmen and one copy of which survived the apocalypse. The information we have in the appendix has some contradictions as well.
The Nonmen did in fact attain immortality, and the Inchoroi, claiming their work done, retired back to the Incû-Holoinas. The plague struck shortly after, almost killing males and uniformly killing all females. The Nonmen call this tragic event the Nasamorgas, the “Death of Birth.”
According to the Isûphiryas, the first victim of the Womb-Plague was Hanalinqû, Cû’jara-Cinmoi’s legendary wife. The chronicler actually praises the diligence and skill of the High King’s Inchoroi physicians. But as the Womb-Plague killed more and more Cûnuroi women, this praise becomes condemnation. Soon all the women of the Cûnuroi, wives and maidens both, were dying. The Inchoroi fled the Mansions, returning to their ruined vessel
That is a contradiction however you slice it. And why would the non men state their shame to men? That they killed their wives and daughters, much easier to lay the blame on the Inchoroi, it is true after all in a way.
Also their some hints of this in the four revelations of Cinialjin.
And he stands in the blackness, the eternal dank that rules the guttural foundations of Siol, his hand upon the neck and shoulder of his daughter, Aisralu, who even now clutches her belly, her womb, groaning against her headstrong pride, whispering, Please… Father… Please… You… Must…
That is the sole curse of the Ishroi, she hisses. He is sack, a net bound about furious, ice-cold fish, each part of him thrashing, fleeing, and he howls realizing, for the first time in ten thousand years comprehending, that he is a thing of meat, that he is of the self-same flesh, the very thing that nourishes him, boar-squealing, bloody and alive. To only hope they had fathered their sons!
And he just… pushes… her… Aisralu… A motion too banal to be anything but murderous and insane, opening a door, perhaps, or closing one, and he feels it, the kiss of skin forming to skin, the hand of the father across the nape of the daughter, thecherished daughter; a push and nothing more, an effort slight enough to slip the nets of awareness, to be no effort at all, and still, miraculously, impossibly, violent with excess, savage, a crime unlike any other; the bare palm against the nape of her neck, her shoulders hunched about a ravaged womb,
It's describing the Womb plague and him killing his daughter, note all the references to ravaged wombs and this his much to soon for him to be killing her to remember. She also says this to him Bakker's emphasis not mine "
That is the sole curse of the Ishroi To only hope they had fathered their sons", As opposed to who fathering them? The Inchoroi of course.
It still keeps with poetry of the idea the King asks for his immortality and gets it at first things seem great the Inchoroi retire and the Nonmen are preparing for a new golden age, but soon they realize their children are different... maybe it's just little things at first odd things for a baby to do, strange actions for a child to take, at first it's just written off but soon they begin to wonder did we make these or did they come from something else. Eventually it's clear that while these look like Nonchildren what moves them is Inchoroi and so rather than let their ancient and noble race fall to the corruption of their enemies, they destroy these abominations and the vessels that made them and set out to destroy the fathers of their children. Alternatively perhaps the Nonwomen cannot bear the shame of their wombs corruption and kill themselves. Remember Nonmen view life and death differently then we do for them living is always a choice.