I respect he isn't your preference but imo they're not even same ballpark.
He'd be...a Mary Sue on like...a human level where he's exceptionally good at things and virtuous.
At least he doesn't have even the gods being like "ah yes thank u for teaching me everything" lol. Rover feels like she's not even one step away from being *walks into a room and everyone falls in love with me*.
At least even the most Mary Sue Genshin characters still struggle with things. I love WuWa designs but there are 0 stakes because a magical solution will float out of my hand.
If people had introduced Kaedehara to me as the Anemo Archon, I would've believed them. My problem with his design is that
everyone adores him, even the Traveller has to heap praises on Kaedehara. (It strikes me that my chosen username seems like a Genshin reference now, lol.)
He can randomly track thieves over considerable distance by "listening to the wind" (hi Barbatos), and though he left Inazuma, he randomly returns in the nick of time to rescue Gorou's troop from an attack, and then he randomly shows up in the nick of time to deflect Raiden Shogun's legendary Musou no Hitotachi which was a feat previously thought impossible.
Then he swishes his cape and "my work here is done."
I haven't played WuWa so I can't say to what degree they share similarities, but I wanted to commiserate that I don't like Kaedehara Kazuha because everyone likes him and he's so well-rounded that, whenever he appears, he is the solution to the problem you're having, which seemed the gist of your Rover dislike.
I'm not going to argue over which is worse, though, I just wanted to share a feeling.