Now I want the card playing AU!

Yes, Ahsoka knows about Vader. That‘s what Baylan is taunting her about when he said „Everyone in the Jedi Order knew about Anakin SKywalker, few knew what he became“.. „Clone Wars“ ended just before Return of the Sith, but Ahsoka found it in „Rebels“ and then had the scene with him with the Obi-Wan miniseries shamelessly copied in its final episode. For a relatively brief (30 minutes or so, I think) „Anakin and Ahsoka: Their Story“ Vid, check out this one which captures a lot of their key scenes from their first meeting (when she’s 13 and he’s what, 19? Directly after Attack of the Clones for him, anyway) to their (until know) last (when he‘s Vader and she finds out):

https://youtu.be/I5THpeMjj4E?si=OWnuOeoaU03qqFt4

Re: does she know Luke redeemed him, given we see her briefly with Luke in „The Book of Boba Fett“, I dare say it must have come up, but I suppose we will find out for sure next week!