@Aidan-Oxley I found another "work around"... duplicate the scene. This has been what I've been doing, but it shouldn't have to be done.
I tried branching, but it's too messy to reload a project to try some other values again. I'm going through the iterative stages of exploring and discerning the right values for jumps, landing, recovery time, acceleration and other characteristics of the hero's movement. It's a LOT of trial and error and testing and discernment to find that right "FEEL", and it's unbelievably annoying to try do this without UNDO.