You'll have to forgive me, but I don't see how you corrected anything. In your original post you said the forearm was drooping an 1/8" down and to the left. I don't see how that was corrected from your photo. I just see a shim that takes up about the kerf of a blade, basically a zero sum game.

To bring the frontend up you'd have zero gap at the top of your cut and you'd need at least 1/8" at the bottom because you used a shim and the two halves where squared up. Otherwise you lengthened the stock. No way around the rails "the barrel channel sides" taking on a V shape in that case. How did you address the leftward twist?
Unless the problem wasn't as severe as stated then the slop in your joint was enough to correct any perceived issue you had.
Like I said forgive me, a warped/twisted stock can't be fixed this way without effecting other parts and functions of the stock.