I'm sure the wings are correct because there is just one wat the framing fits.
The internal structure is preshaped so that the dihedral is given.
I also use laserframes,so there is no error possible from my side
When making the internal framing for your F15 , you have to be very precise in your cuts,do a lot of dryfitting and be sure everything is properly aligned before you put the skins on.
I'm not sure how many papermodels you have done?
But it can be quite easy to get things a bit twisted.....