It looks like the wing is warped span wise, right? And it's only on one wing panel?

I'm one who likes perfection or at least close to it when it comes to building my projects and if it were mine, I'd just build another wing panel. It doesn't take too long to cut things out and it looks like a very simple wing to build too.

You can probably use most of the same pieces, except anything warped of course
About the soaking and twisting it back into shape, it works but I've only seen it done when the twist is chord wise. Same thing on the fix with the covering.
I've used amonia sprayed directly to the wood, twisted and held in place with weights and shimed with anything I could come up with