FYI, for examples of what all those easing animation speeds look like, see easings[dot]net.
What I was looking for was a simple, straightforward plugin that just animated page scrolling to targets IDs. This one does the scrolling part well, and has an unexpected useful feature of declaring a vertical offset option.
The easing feature doesn't function at all on my WP install (5.8), all I get is a linear movement at the given speed. I'll try and troubleshoot it and will update this review if I can get it to function.
The other problem is the interface. It looks like they must have really had fun making it, but unfortunately forgot about the user a bit. Most of us aren't playing with our designs, we're trying to come up with something usable and attractive. Good design is subtle, even invisible. Less is more. I doubt many people want bouncing and elastic effects. Their default ease option is easeInQuint; slow at first, then rapidly accelerating to a halt, which often may be what you want. Their plugin page shows an 'elastic' setting as the first example. I bet about 2% of users are interested in wacky effects like that, or double-bounce, etc. - and close to 100% will have no idea what easeInOutQuint looks like. The default ease in most editing & animation tools is ease in/out, though which is usually not called easeInOutQuad. For some reason they put that one at the very bottom of the list.
Visualizing browser scrolls based off mathematical terms like quadratic, sine, exponential waves, isn't appropriate or necessary here. Using the standard set of names like ease in/out, ease in, 'easy ease' (just copy Premiere) would make more sense. I mean, not to brag but I took 300 level math courses on waveform analysis, and I had to look them up, if that tells you anything.
So my advice to the dev(s) is to update your settings interface so it at least shows pictures of the curves, if not a small sample animation alongside them, or at the very least describes them in the screenshots - and consider ditching the math words.