You're gonna be bothered by how cool I am.

I actually agree with you that she understands Hermione rather well. I don't care much for her portrayal of Hermione on the other hand but I think very little of it has to with Emma herself. I think the blame lies with the directors because Emma does something I think Hermione herself would do if she was (real and) an actress, she overthinks her part, I can almost sense the running commentary of explanations that appear to be running through Emma's head during her performances.