It's junk inside. The ribs are thin and punky wood, the main spars are some kind of hardwood, which is okay - but the rear spar isn't one piece of wood at all. It looks like blocks inserted between each rib, which is a crazy way to do this.
Major surgery underway. I ran the leading edge off in the band saw, then cut the wing apart 1/2 way through the rear spar. I'll replace both these with full-length spars, then cut through the attachments of the shear webs with the whole thing pinned down flat. Then replace the shear webs and it oughta come out pretty flat.
I managed to cut out all the shear webs and broke only one rib, but the warp is still in there pretty strong.
I'm surprised there hasn't been inflight failures of this wing, as heavy as some of the finished models have been.