Hmmmm, I would have probably used a lerp (0-1), and done a lerpRot. Then I would have probably had a multiplier in between the timeline and the lerp rotation alpha… the Multiplier would default to something like let’s say 1 (so you can use the 10.5 in timeline), and the alpha would be the same… for the reverse. But for Play… right after the OnOpen event, set the multiplier to something silly like 10 or something, and clamp it to 1 (since it’s a 0-1 lerp). Right after the OnClose, set it back to 1.
I mean, truthfully, you’re using timeline in a “wrong way” so it’s just hacking together some solution that would work for you.