Sounds like you are not sheeting in enough, if the wrinkle runs from the tack upward on the leech.

Sail shape is important with the Wave, and basically because the mast is almost round, in designing sails we have treated the boat as if it had a fixed stick. So, we design the draft farther aft that on a wing-type mast.

I don't know what sail you have, but normal battens seem to work well, and sanding has not been on anyone's format. None of the top sailors do any sanding.

I will say this, on several sails I have they have a lot of fullness and I do very well in light winds. However, when the wind gets over 10 I need to stick extra stiffener battens in the bottom 3.
Rick