At least, she should be more willing to fight for the possibility that a criminal/villain can be redeemed.
Sure, that's part of her code, once she starts to get over the suicide business. The thing with Alpha is a great example. But notice that the thing with Alpha was all her. She lies to the other Bats about what's going on. Even once it comes out that "hey this guy's the criminal" she doesn't tell anyone what she did in giving him a chance or try to explain herself about redeeming him - she thinks Bruce would disapprove. Because her understanding of the Batcode doesn't include redemption. It's why she leaves to find Shiva when she wants answers, why she ends her series by declaring, "I'm not Batgirl, I'm something else."
When being punished was what she needed, she sought out someone who would punish her. Her whole understanding of that relationship was built around that punishment. Yes, she outgrew the need, but outgrowing the perception doesn't particularly follow. Rather the opposite, in fact - it's a natural part of adolescence. When you're a kid, you need your parents for certain things in a certain way, and then you stop needing those things, and you decide they're useless. It's only after you grow up even more that you finally understand they can also offer you different things in different ways that are just as helpful and important. Cass isn't there yet with the Batclan, she still sees them for what she wanted from them when they met.