Yes, these are both the kind of thing that I'd accept as "earning" a redeption arc, or at least steps along the way. It wouldn't even have to be specific to Erynn, IMO. Maybe he sees Ethan creeping on other models and blackmailing or otherwise compelling them to do things they don't want to do and Zach intervenes to protect them, or maybe Ethan goes too far in planning revenge and Zach has a wake-up call of "hang on, I don't actually want this" and stops going along or tips off the MC with a warning. I don't know what it would look like exactly, but I do think redemption is possible.