I highly recommend watching the documentary they produced, https://t.co/y70yeZ3ZjY?amp=1 . My takeaway is that it took 14 years to produce a working kite and in that time conventional wind turbines became much more economical and efficient. After realizing this, they pivoted to doing off-shore wind generation because the cost for competitor products was higher. They had one somewhat successful test but were out of money and couldn't find any other investors.