Landings are often hard but they do land stuff from those heights. My guess though is that they're going higher than expected due to the high winds, since the way to generate height on a windsurfer after jumping a wave is to let the wind grab the bottom of the board and lift it up, so at 80mph it's gonna give a shit ton of lift. It's not like kiting where you can float up and down, but then again you can't kite in 80mph winds unless you want to end up on the moon