Actually it was just that lone thing in the level. The only other thing going on is an add rotation of +0.75z to another component of the actor. That is on a separate timeline. I’d make a video real quick but I already moved on from Set Relative Location. What it was doing was freezing and jerking. It appeared like the adjustments were coming in at random, spaced intervals instead of continuously, parallel to how the ticks seemed to be randomly coming in on the first attempt.
Here’s my (compromised but) final result:
Jing
And here’s my “equalized” curve:
What you were saying about calculus appears to have been the root issue, although I still don’t understand how the movement doesn’t follow the values on the curve line and instead acts unpredictably.