I like Manaria but feel like she doesn't really make sense within the otome setting.
If this were just a story about a commoner in love with a noble, then it would make sense for a character introduced as the stock rival-from-the-love-interest's-past to be comically overpowered compared to Rei - she's supposed to seem insuperably better than the main character.
Rei's already the comically-overpowered protagonist of a completely different story, though, and in that story Manaria's just a minor supporting character, so it's kind of odd that she's also just coincidentally the Avatar.