Looking great !!!
Yes, the right sponson definitely needs the reinforcement to the turn fin area.. unfortunately we discovered this half way through the season and several boats and kits went out without the new mod...I have tried my best to inform everyone of this. It's an easy mod to do without having to destroy half the sponson!

When building the kit, you can reinforce it anyway you feel is adequate, but the 1/4" pin method is holding up very well so far and can be done post-build. The issue really isn't the strength of the sponsons themselves, it's the torque applied to the rear of the right sponson...as the boat turns hard, the bottom of the fin is being pushed away from the tub as the top of the fin is pulling on the inside/top of the sponson towards the tub... this puts a WHOLE LOT of strain on that piece of 1/4" ply. The fin is trying to TWIST that piece of wood and it really only has the 1/16" ply sheeting and the filler material (foam in most cases) to hold on to. The 1/4" pin mod takes this load and carries it over to the other 1/4" ply stringer inside the sponson so the force is exerted on both pieces AND the filler material sandwiched between them. As long as the pins are securely bonded in, you will bend the fin before breaking the sponson...I tried it!
A brace from fin to tub could help I guess, but it would have to be bracing the very top of the fin... this kind of brace is normally used to stabilize/adjust long turn fins that extend behind the sponson...not the case with the Warpath.
I think if you made a doubler that's thick and screwed in with the fin bolts and was threaded for a stiff rod going to the tub that could help I guess, but remember its TWIST we are trying to eliminate, not side to side movement in this case... in short though, any extra bracing is almost never a bad thing!