For keiso house, read "geisha house", at least the polite and perhaps bowdlerized definition. Keisos are social hostesses who grace high society with music, dance, art, and service. They do not put out. (Unless you're extremely rich, and then there's a formal contract which includes property and child support clauses.)
And then there's the mage's house, which is a high house of shadows and secrets and doors that open to obscure spaces in the middle of the night. My favorite trope!
I haven't read Neumeier's other books, so I don't know if this is her normal style. It is a direct homage to Patricia McKillip, I know that; thus was the book was recommended to me. We get the mage's house in the first chapter, and I'll give damn near anything a chance if it does that well.
Weirdly, the book does do the house well. The setting and the language work. The magic works. The characters and the story, those fall flat. That's the long and short of it. Imitating McKillip: not as easy as it looks, and it never looked easy in the first place.
Karah, the prospective keiso, is not interesting at all. The narrative (not just the characters!) makes much of her wonderful innocence and sweetness -- these being properties that might be spoiled if she is exposed to nasty spiteful people, such as the one nasty spiteful girl in the keiso house. I don't think I can express how little I care about that character arc. She should have spent her time learning to pick locks or tell dirty jokes or something. Woulda made her a better conversationalist.
Mage Ankennes starts out as an interesting contradiction. He is a patient and nonjudgemental, if cool, teacher to Nemienne. But he is also involved -- patiently, coolly -- in a plot of extortion and assassination. We see him from two contradictory perspectives, and I was keen to see how that would be resolved. Boring answer: one of them is wrong. There's no story between the student and the master because the master turns out to be the villain of the piece. It's not even a surprise betrayal; the reader suspects it by chapter 3.
Nemienne is not exactly boring, but she is seriously upstaged by Taudde, the bardic sorcerer caught in Ankennes's web. Taudde has choices to make, and if he starts off wrongfootedly with "Sure, I will let myself be blackmailed into murder" there's at least some level of consequence to it. Nemienne falls into things and survives them. We're told that Nemienne wants magic, but we see that Taudde needs magic, and that's where the story is.
And then there's Leilis, the middle aged failure of a keiso, who... I'm not sure what she's doing in this story at all. We're told that she's cursed -- to touch her is painful. So, okay, why does that matter in the keiso life? People aren't supposed to touch her! There's at least one keiso we meet whose skill is dance; she's never going to become a paid consort because her dancing brings in more money. So...
Look, I'm spending too much time on this. It's supposed to be an intricately jeweled fairy tale. But McKillip can make this sort of thing make sense, on some emotional level. Several emotional levels, in fact. The fact that I'm questioning this book's logic means that it's already failed.