"High-altitude winds between 1,640 and 3,281 feet (500 and 10,000 meters) above the ground are stronger and steadier than surface winds. These winds are abundant, widely available, and carbon-free.
"The physics of wind power makes this resource extremely valuable. “When wind speed doubles, the energy it carries increases eightfold, triple the speed, and you have 27 times the energy,” explained Gong Zeqi "
An untethered AWE cannot produce any power
Contentious. Thethering increases power production by restricting the “sail movement power”. The blimp part is highly/perfectly aerodynamic, and the betz limit means that a turbine does not fully “act like a parachute”. Ground vehicles that proved faster than wind speed directly upwind could use similar principle to turn a propulsion prop, that increases forward/apparent wind speed generating more power.
This relates to same incredulity for faster than wind upwind ground experiment, and needs experimental proof. But principles of sailing are indeed magical, and simply generating enough power to move forward is extremely useful, even if tacking were needed.
In all your examples there is the ground to provide a counteracting force. Maybe I am misunderstanding what you mean by untethered, but any initial airspeed difference between the wind and your system will eventually vanish and you’ll move along with the surrounding air.
I co-founded an AWE startup 8 years ago and let me tell you, literature does not support your claim.