I see what you’re trying to do but wouldn’t it be easier (and more logical and less prone to errors) to apply damage when you land, rather than check for it 10x per second - which I believe is the root of the trouble here. Check this out:
Using a curve for this works really well, and you can have more than 1 curve if players acquire an ability to reduce fall damage or are Ninja Wizards, for example. Consider it.
