If I understand correctly you now have stab tubes that work and just have a canopy problem.
Well.. just fix it , either add 1/2" of balsa to the leading end of the canopy and redrill for a new hold pin or make a backplate for the back of the canopy and sand it to fit and cover it. In the world of arf's as in almost any other manufacturing you will have run differences and you will just have to make it work. True you probably shouldnt have to do this but If you want to get to flying.......