Single-unit-kite concepts were not properly conceived to reach high altitudes. The proper way to fly highest is by multi-unit kite trains. The principle is precisely the same as multi-stage rocketry to achieve orbit; each stage carries the next higher.
Train Record 9740m 1919, over a century ago.
Lindenberg - historical world attitude record in 1919 (fang-den-wind.de)
For efficient Kite Trains today, we need to ask ourselves: who are current KiteMasters in our midst? This is where @Rodread and David Santos Gorrenna Guinn come to mind. Apart from being a veteran Aeronautic Roboticist with known connections in NASA; DaveS (USA) has had the honor to learn kite train practice by the greatest historians and practitioners of our time during a 7yr residency at the World Kite Museum (Patton, Diem, Busing, Hassan, etc.). He got to know Walter Diem, Germany’s greatest kite historian, at Fanø.
He affirms and I concur that: "Train topology was the standard method for scaling kites to altitude. Layered AWES can once again work at 10km, by the same principle-
One can scale horizontally as well with many-connected topological stability.
10km high? Of course, we can get there, harvesting AWE at every level in between. Our super-polymers are 10x lighter for the same strength than the piano wire that did it long before. Graphene will be 10x better still."
DaveS had always maintained from earliest Makani days that ‘Kite Trains’ is a critical AWE research direction being neglected by industry members, some of whom have burned through much investment (Makani, the lion’s share), but will never fly high, because they don’t practice multi-stage AWES.
Can sincere full disclosure of AWE R&D accidents show that no life has been lost to date in mishaps? More people may yet be saved in the course of AWE R&D through optimal research design.
My sincere appreciation goes to @Windy_Skies for this opportunity to rework my earlier version of this post.
Best lifts.