Shadowheart doesent really come across like a CHA14 character hence why ive given her the CHA stat of 10. She can sort of try to use her charms but she still comes across as cold and calculated, not really CHA14 material xD.
Remember that CHA is not being charming, it is the force of your personality. It might manifest as being happy and cheerful and likeable, but might also be brooding and glowering. It is about influence rather than charm.