As a possible Esmerada I think Jessica Findlay-Brown would make a good choice.
She has the right look as she is has an olive skin tone, black hair and she’s young enough to pull off the role.
She is a fairly decent actress though she hasn’t been to many thing but her most notable role was Lady Sybil Crawley on Downton Abbey which isn’t the most difficult role in the world admittedly but neither in Esmeralda.
But another great attribute she has is that she is a former ballet dancer so she can bring a dancing aspect to the role.