The harassment incidents to me honestly don't seem to be the most relevant part of the lawsuit. HR ignores your complaint, yes it is wrong; people make mistakes occasionally, it isn't a lawsuit situation, it's a "send another complaint" situation (or "contact the director"). HR repeatedly or even systematically ignores complaints and you start to have to do something about it.

But the unequal pay, promotions, projects, and participation? That is a rather unequivocal situation.