[Racket? You definitely mean the best rock 'n' rock in all of Liyue. Besides, she wasn't raised to be completely uncivilized. It wouldn't sit right with her to let him struggle with all these books.]

I don't think this is Teyvat at all. This tech stuff is more advanced than anything we'd get from Fontaine or Snezhnaya. I don't know the other regions too well, so that's my guess anyway.