Landed on this. Looks good enough

And on the character (and overriding the blink anim when catching the fish to go >.< in effort)

What if you use curve atlas to just draw your timing?

That's a good idea, and probably a more simple way to do it, but I figured that'd be an extra texture lookup that I'd like to save and just do with math instead, since this material is already pushing it with texture samples!

wait wait wait wait wait wait wait wait wait THERE'S CODE NODES NOW?!?!?!?!?!?!?

Custom expression material nodes have been available for a very long time! :)

You could also control the curves with a control rig. Minute 22:10 or so:

how did you end up calculating the blink frequency?

I messed around in desmos for a bit turning knobs until I got something that looked okay 😆