… and of course whatever effort that is necessary to arrive at the right amount of roll stability knowing not only that the wing would deflect like that, but how much it would under which load conditions. The results of that analysis/understanding would have to be “baked into” the design, which is my point.
The deflection may be a “secondary, known effect” of the general structural design, but the aero guys involved would certainly have to know what those deflections looked like all through the flight envelope of the airplane and do whatever else was necessary (including having the structures guys redefine the composite structure‘s characteristics) in order to arrive at acceptable handling qualities. Torsional deflections would also have to be looked at, and characteristics tailored to have the controls work properly and to avoid flutter, as well. I wonder if that particular sailplane uses spoilers only for roll control rather than ailerons….though of course you can’t pick up a low wing with spoilers, as some B-52 pilots have found out much to their detriment.
It’s far more nuanced than “oh, the wings flex, giving us some dihedral effect so we don’t have to build any into the jig shape of the wing, so isn’t that handy.”
While I wasn’t an aerodynamic configuration designer, I am an engineer who helped design airplanes for a living.