RE: Maybe I'll call it "Warp 7"..
I think the delta has just been sitting around a while and the epoxy just flowed, yielded or it was near a heat source. Perhaps its own weight or something sitting on it.
Try some opposite twist focused on one area at a time. Id start with the left wings excessive wash out, the left elevon may come back on its own or be much less. Twist it for a few hours, or days and check periodically to see if it progresses. Not too much or it could delaminate somewhere.
I had a skinned hinge on a Whiplash crack several inches and I feathered the area out and used light Kevlar mat to repair, a lot of work. A few flights later, the stock control horn failed on the other side and that was the end of that plane. They are tuff but there are limits. I got to see the inside of it, not impressive.