Ah. Just read the thread you linked to which points to Lo's own opinions, and yes, I wondered if that's what she was going for, as respects to "I won't describe race and I will let you make your own decisions". I tend to disbelieve that this world, which is constructed (a) to have cultural and political colonialism in the form of the Philosophers and (b) there's a vast historical sense of importance tied to history of place, is one in which physical descriptors which show you as having ancestry from Elsewhere is not important, and I would want her to convince me of that (as she convinced me that sexuality is not important despite the societal markers of heteronormatively).

With the author's background and your comment here in mind, I chose to read the characters as primarily East Asian and white as a mix, but I don't think I would have done that if I hadn't had extratextual pointers telling me to. I've been trained in how to read Fantasy Britain, you know?