If you're running the script currently, I'd suggest updating to this one.
If you haven't given it a try and have after effects, this would be the version for you to try!
Why is this such a big deal? Because After Effects doesn't allow you store values from one frame to the next, it also doesn't play nice with recursive functions. This is a problem because of the way sine and cosine work for the bounce part. If you change the rate on frame 10, after effects assumes that current value as what is was the entire time... which leads to very interesting results with the curves running backwards, extra slow suddenly fast, or just stopping. I couldn't think of a way to get around this until now.
Time = Frames * FrameDuration
I don't know what started this, but this little equation lets me control time by knowing the frame and frame rate (duration). The frame rate is set by the user in the composition, but I can control the frames... specifically the frame count. The script adds up the "frames" that have happened and adds weight to them based on the rate at that current frame. It has 2 downsides: It's 8% slower than before and it can only interpret a change of rate as linear changes. Eh, not a bad trade off.