Hey!
So, one small thing, "fix the fucking skin" is probably not the best way to get someone's attention regarding what you're perceiving as an issue/bug. ;)
PROJECT: Yasuo had entirely new animations, and the issues you're describing with him was that, there were 2-3 extra frames in a couple animations, which threw players off. He wasn't using base animations. In that instance, it was an error on our part - we wanted to make cool animations, and while we did playtest the skin, it wasn't noticeable to players who didn't main Yasuo. Of course, we've updated how we do playtests since, and call in the mains when we change up animations!
On the contrary, Dragonblade Riven is using base animations. The only 'new' animations she has added in the kit itself are ones that help animate the additional hair pieces, as well as the tassel on the hilt of the sword.
I think what may be throwing you off is, the difference in SFX, especially when you're using your Q. We saw similar comments when we put out Arcade Riven. The new SFX are obviously different, which can make a skin 'feel' different than what you're used to, especially when a lot of her earlier skins don't have new sounds, and simply use the base.
Case in point, I don't play any other skin aside from Arcade Sona because the base/other skins feel 'off' to me. It's a symptom of me playing that skin, almost exclusively, since 2013, but there isn't anything inherently wrong with the skin itself, in terms of there being bugs.