This might be my second most anticipated game at the moment, after Pyre.
For the range marking, I think it could fit the style of your game to have the ground plane just change color in an area around each character. I think it could be made to look like some sort of corruption or force that's spreading out from each character (which would be more convincing if the range box left behind a fading trail so it doesn't just look like the characters are running in place on top of moving platforms).
Basically a better version of this:
It could be possible to roll the health bars into that visualization, since I initially thought your health bars were hitbox markers when I first saw them. Anyway, just an idea. Feel free to take it or leave it!