What makes you think she knew anything about Jean-Paul whatsoever? They interacted, like, twice, and didn't exactly talk about their pasts, as neither of them is the type to. And it's not like Bruce was going to tell her anything that didn't involve how she'd failed or who she should be punching. Which pretty much excludes any chance of her knowing Eddie used to be a criminal, either, since why would he bother to involve her in anything involving him, where clues and literacy and thought would be required?
You're giving Cass way too much credit for curiosity and Bruce way waaaaay too much credit for competent education.