I would argue that Shadowheart is more evil then neutral due to worshipping an evil Goddess, Shar.
She just wants to be cured and return to Baldur's Gate without being entangled in all the drama or people in the area. Sound like a neutral character to me.
And you need to win a hard DC to know about Shar, without that meta-knowledge, there is nothing evil about her outside her opinion that Selûne sucks (and you don't need to be evil to think that).
