I remember building a Stuka balsa wood and tissue paper rubber band powered plane. The wings don't actually seem that hard. Each wing would just be two pieces and then sand the ends into a tapper. Similar to how Bixler sanded the wing ends of the Versa Wing. But at an angle. It would be a lot of: sand a little, check it, type of thing. And it would be hard to get the two wings to match. But it is certainly possible. Actually the wings would be a total of 5 pieces including the straight piece under the fuselage and there would be four joints to line up perfectly. But hot glue works as a great filler if it's over sanded.
The Corsiar would be harder because of the curve of the gull wing. earthsciteach is right that the Stuka would be easier because of it's boxiness. To get the proper curve of the Corsiar you'll need a curved spar and to remove a lot of the paper from the foam board to get it to bend that way. Or use wire as the spar and bend it to the proper curve. If Flite Test is serious about making more War Birds and serious about making the Corsiar, they should actually do the Stuka first to get the right build up of difficulty in builds that they want.