I imagine one of the challenges would be getting up to foiling speed in rough waters. From the videos I've seen, once the hull of a foil boat is out of the water, the ride is much less affected by waves.
they take off at around 7-8 knots, so as long as you can get up to that you're good. the motors and wing stay well below the water, the candelas do wave detection as well IIRC.