The fact that Diana's rogues gallery is ignored is kind of a separate, but connected, problem. Just like her rotating supporting cast, constantly-changing setting, etc. To fix one, you have to fix them all and establish consistency.
If that inconsistency isn't a problem, then yes I think redeeming *some* villains is not only possible, but a good idea. Not the major, A-list foes who we'd consider Diana's classic/iconic rogues gallery (like Cheetah, Ares, Circe,) but someone less central in the bad guy list? Yeah, absolutely. If you want to show Diana's compassion, her successfully redeeming a villain is a great way to showcase it.