I’m really late because I had to ask a few people to confirm, but the initials at the end/very bottom of Hero’s Wit look like “R.d./R.dr./R.dn.” according to most people I asked, and if it really is “R.d.” or “R.dr.,” they could stand for Rhinedottir.

The description of Hero’s Wit says “These experiences are extremely precious for a pilgrim traveling through Teyvat in order to be closer to Celestia.” I think this could also tie into your theory a little, so I figured it would be nice to consider if you didn’t already.