Might be just me but the hair is backlit as I'd expect and looks right. The hair in the shade is dark brown as I'd expect from your description of it and the model's ethnic background. Her skin looks right for a contre jour shot. If she looked "brighter" it would look false. She is supposed to look "shady" in the light conditions sense of the word.
In other words, everything looks right and fits the light conditions. I'd change nothing but as I said that's just me. I may be in a minority of one.