Well i wouldn't expect any horse archer to carry a team, i have never even seen a horse archer ever carry a team in a round before, ever.
So if i was you i wouldn't expect to get alot of kills as one. But i've never played any type of horse ranged so i don't know what its like for kills.
Yeah I don't expect getting many kills either, it's more like a fun/RP build combining all three: melee, riding and shooting, in one character.
Although, I've seen three Reborn horse archers teaming up and becoming pretty dangerous, but I guess they are all pure HAs