The laddermill is difficult to implement. And the downwind motion destroys any eventual “crosswind” component of flight. And some other arrangements to achieve a crosswing flight (left and right around the main tether) are complex. See also the discussion on Laddermill.
So even their developers dropped it, @dougselsam for SuperTurbine ™, Tu Delft for yoyo method as shown on the page 3 of https://kitepower.nl/resources/lansdorp06.pdf .
A crosswind system with a wing flying by eight or loop figures faces to an irregular power due to the various tether angles; in comparison a rotating device like RotoKite (working by yoyo method) is less efficient but doesn’t suffer from this as the main tether doesn’t move laterally.
A yoyo system faces to its intermittency. Perhaps several unities could compensate it but the management doesn’t look easy. Batteries are expensive, polluting, and lifetime limited. Supercapacitors have a too low autonomy. All temporary storages add significant costs.
Adding a low efficiency (4/27) per swept area, although a high efficiency per wing area, a low power/space ratio when the crosswind method is used, becoming better when a rotating device is used, the requirement of a gear as it scales…
There are perhaps good AWE designs, but they are not still known.
I think that finding the good design is more in the domain of discovery than of invention, because of the many parameters.