Its quite normal to estimate numbers loosely without excess precision. If needed, simply raise the rated wind velocity to match a desired number. 15msec is not unreasonable. Let the Hydra test be a data-point rather than a final determinant of what a 200m2 kite at 500m can do.
The 200m2 size was chosen conservatively based on being far easier and more certain than SkySails hoped-for 1000m2 unit. I am not ready to adopt 1000m2 as proven, compared to all the KiteShip and SkySails wings closer to 200m2. All this is “solid” to me, since Ship Kites is where I started in AWE, under Dave Culp, who also insisted that high L/D was the wrong figure-of-merit.
No surprise that new developers easily overlook what DaveC learned by being 20years ahead of everyone in power-kiting. No mystery why the massive Inuit WindSled flies an NPW to cross ice caps, nothing better exists yet. Soon its going to be generating its electricity as well, by rolling a wheel-gen. The other kites can stay home.