So here's a small tweak that fixes the worst of that. Now instead of rolling down the stairs, Geralt will do a quick little stutter step and keep on moving.
We can't get a perfect fix. That could only happen by actually fixing the steps and walk paths down certain ones, so the game didn't believe Geralt was falling onto a slope. But this fix is much less immersion breaking than the vanilla game.
Try it yourself on a set of problematic steps. Feedback is welcome.
Like this mod? Check out my other mod, Immersive Cam, here.