I noticed Powertoys had that capability, but wasn’t sure that’s what you were talking about. I can’t say 100% this would be okay under the new guidelines, but it’s just a Microsoft Utility program built by Microsoft to do things Microsoft already can do (but makes it easier).
Not knowing enough about the remap functionality, I can only say that if you remap Alt-Tab, make sure that’s all you do with it. Don’t incorporate the “t” into anything except Alt-Tab. However, I can’t guarantee this is 100% okay with Blizz. Even so, I don’t see how it’s any different than remapping my mouse buttons. Just don’t macro anything outside WoW.