Your moisture dome is only about 8" tall, so you're probably limited on height there. You should expect some of the cuttings to shoot out some sprouts before they're ready to graduate to cups or potting soil, and if those sprouts or leaves touch the dome, they'll rot.
This year I'm doing sphagnum besides rooting cubes, and skipping the cup stage on the sphagnum cuttings.
The rooting cube is good, but you can't separate it from your cutting when it starts rooting, and last year
it was difficult to keep the moisture level right at the cup stage because the cubes dry so quickly, and you don't want to overwater at that stage.