While I understand why you’re upset, I have to second my delicious looking friend; haste makes waste.
While I think, personally, the idea of a Sylvanas redemption is too contrived based on how they did her in BFA (for the most part), I feel Blizz has laid down enough significant groundwork through actual visual storytelling to make it a great deal more reasonable.
Personally, through the way they’ve portrayed some of Sylvanas’ reactions, I feel she had a strong case of buyer’s remorse and she will be redeemed through the process of the actual merging of both her Banshee Queen personality and her High Ranger General personality.
Hell, I’d be surprised if, somehow, she didn’t ascend to fill the role of Archon or even a nee Jailer, albiet a less vengeful and more just and impartial Jailer as a true opposite though equal partner to the Arbiter herself.
Remember, Sylvanas know how terrible it is to be turned against one’s will into something that is anathema to one’s original being. And the Jailer has done so to Anduin. She’s no dummy. She knows she’s done wrong and been wronged. She must know she must atone for what she is truly responsible for but is not 100% entirely at fault.
While I don’t believe she can go back to Azeroth, I do believe she can be truly redeemed and, my guess is, so does Blizzard.
I won’t say you’re wrong to be upset, but I’d also caution against leaning too much into your initial feelings. If Blizzard has done nothing else this expansion, they have demonstrated they can write a compelling story with multi-faceted characters. So be wary, but don’t lose faith.