Ill explain what evidence I saw of the RBR front wing flex
It is the front wing adjuster that allows the movement, The adjuster pod was pointed out above. In the scrutineering bay a hand pressed down with just finger pressure on the top of the adjuster, this was rigid as youd except. Then shape of the pod was squeezed, its squashed like the bulb on a bicycle horn! Then the hand pressed down on the slotted section of flap just next to the adjuster, the wing deflected very easily. I mean this was not a hefty push with the palm of a hand, more like moving the lid on your laptop. As the wing deflected the bulb deformed too, both sprung back to their original shape as soon as the pressure released.
As you can see the adjuster pod is all black, but thats because since China its been a part made from metal (alu..?) and something black. Before that it was one material and painted the same colour as the wing. Ive got pictures of the pod and assumed at the time that as it was matt black that the material was carbon of some 3D resin to create the shape. It seems it is a rubber-like material.
Therefore its proven that
1) the pod is flexible, as its counted as bodywork, that alone is in contravention of 3.15.
2) the top of the adjuster is not rigidly connected to the flap below, what appears to be a fastener running from the hex headed top through the mount on the flap is clearly not. It was suggested a leaf spring was employed within the pod between the top of the adjuster and the flap, I havent seen the insides of the mechanism, but clearly some form of sprung element allows a large degree of movement for very little force. It was suggested by those who have compared it directly to other teams wings, that the RBR flap is 4 times more flexible than its rivals.