The mystery carbon tube is part of the wing peg. Dremel out a hole in the wing saddle where the peg goes. Make it oversize. Put some sika, silicone, whatever, on the outside of the tube, put it in the hole making sure the glue fills the gap between tube and hole and fit the wing with peg and let the glue set. When it's set you have a peg hole in perfect location retained by a kind of rubbery bush.