The Moe up the Butt tag kind of gives the wrong impression here since this art syle isn't moe. Maybe consider adding Non-moe art style.
I think the moe tag works for this because the story is super cute. I don't think the art style matters much when it comes to labeling something as moe, but this art style is pretty girly so I think it counts as moe anyways.
I'm honestly not picking up any intentional yuri vibes, their relationship feels more like that of a big and little sister to me, or like a mother and daughter. Not protesting against the subtext tag though, it's a whole intention vs interpretation thing.