I'm not sure that the Gliders are much like the High Ones at all. They may have retained the overall physical appearance the High Ones chose for the World of Two Moons, and retained some of their powers, but that's as far as it goes. The Gliders are trapped in a status quo of their existence - I think at first they didn't want to change, and now they can't any more. It's no wonder that they can't Recognise and conceive with each other, their whole existence came to a stop. Whereas (if I remember correctly) the High Ones were ever-changing and on one endless trip of exploration to learn new things?