Pet peeves (beware some RotE spoilers)

[Nuytsia]

I don't know if we have any evidence that she is physically adult. People certainly found it shocking to see her dressed as a grown woman at that ball she goes to by herself, so I'd say she her appearance at least is not physically adult.
I would say that RH is definitely exploring the issue of 'when does a child become an adult' in several of the characters, and also the consequences of a child pushed into an adult world too soon (Wintrow, Kennit, even Althea, Brashen). We even have a liveship that is a mix of man and child!