That is certainly the case on my Nimbus 2 where the main spar is joined and secured with a main pin but can still essentially float around in the fuselage if it were not for the lift pins on the wings.
Hence the name "lift pins" - they carry the fuselage load.

Yes, I guess that's probably more correct, as the lift pins are mounted to the internal structure of the glider. (Generally, a steel tube cage that incorporates the landing gear and all other structural components.) The spar carry-through hole is primarily surrounded by composite structure only.

My bad.