Actually I don't think i mentioned polishing the bar where it meets the frame, I was talking about where it meets the metal of the slide being polished, and where it rotates against the trigger. I did flatten the side a bit and removed the oxide layer, but kept the grooves to hold grease.
As for the firing pin block, the P-07 works a little differently than some of the striker fired pistols I have. On my XDM pistols, a lever is raised vertically and presses the center of the block. On the P-07, the thin lever rotates up against the side of the block. This causes the block to slightly tilt in place before it moves upward. If the sides of the block are not smooth, it can bind against the slide, and cause a VERY large increase in force against the lever, much more so than the block spring. This of course manifests as stacking.
I am not saying what you have done does not improve things. The back of the trigger bar needs to move a lot of stuff. The total movements of action and their points of interaction can introduce multiple stacking forces. In fact, chances are high that i did polish the exact area you are talking about, I did a lot of stuff to the gun when it was apart.