If you have a Private Glider or Commercial Glider rating and want to fly light sport glider, I don't see the problem. You are already qualified to fly a glider above 10,000 MSL.

If you want to fly a self launch or "motor glider", it's a glider, that may qualify for "Light Sport" because it is speed limited. Get the self launch endorsement and go fly.
You do not need a "light sport" rating.

If it's certified as an "light sport airplane", then you need a light sport airplane rating, 8710-11 completed with two qualified instructors after training.

Is the mud getting thinner now?

BillT