I found that the partial data (we don’t have the wind speed, which can nevertheless be more or less deduced from the reel-out speed) do not seem to indicate a very high power for a gigantic 5000 m² parachute.
Concerning the surface area of 5000 m²:
If the projected area is considered (in case the 5000 m² is not the projected area), the drag coefficient Cd would be just above 0.5 instead of being below 0.5.
In this case, compared to a smaller 139 m² parasail, the power per m² would be about half, at a supposedly comparable wind speed (10-12 m/s). If this is verified and if the Cd of the 5000 m² parachute is comparable to the thrust coefficient Ct (lift and drag combined) of the 139 m² parasail by considering equal surface area for both, massive scaling up would lead to a significant reduction in power produced per m². Is it due to Reynolds number? Of course, I reiterate that I do not have the wind speed at the height of the parachute.
This leads me to wonder if such limits (related to the Reynolds number or for another cause) would not apply to all soft kites, whatever drag-based or crosswind power kites. For example I experienced a small power kite, seeing that the increase in traction was below what I expected when wind speed doubled, which I hadn’t noticed with a small kite parachute.
Rigid kites or blades (see regular wind turbines) probably behave much better at high wind speeds, or when larger, i.e., with a higher Reynolds number.