I honestly wonder how much Roswal knows or doesnt know. He certainly has this "knows pretty much everything"-aura about him. And I think I said this before, but it's just irrational that he'd honestly expect a normal guy like Subaru to achieve all the things he just "like that". I know there's the possibility that he planned for Emilia to fail and just takes Subaru's success as a nice bonus, but even then he should be curious about how he does it. Also didn't Beatrice actually remember Subaru even after he dies? I think something like that was shown early in S1.
Btw have talked about Elza? I just wonder: What makes some characters SO strong? We've seen 4 characters that overpower the rest: Roswal, Reinhard, Elza and Wilhelm. I'm excluding Beatric and Puck because they're otherworldly beings. Roswal is mysterious magician, Reinhardt a prodigiy and son/grandson of Wilhelm who whimself is a seasoned hero. Does this mean Elza is also more than just some assassin? I mean, sees even beyond someone like Betelgeuse. Subaru managed to evade Betelgeuse's attacks, but he can't even see Elza's attacks coming. So this is why I'm wondering if Elza is also some witch or otherwise special "being".