Weight Map Symmetry Issues

Faux2D

I know it's a buggy feature but I'm keen on finding a fix. Whenever I copy the weight maps from one side to the other (Weight Editing -> Weight Map Symmetry -> Entire Figure) some weight maps get transfered to the wrong bones. About 95% of the figure is done correctly but those few maps that get placed on the wrong bones pretty much ruin the whole figure.

The geometry is symmetrical. The bones are symmetrical. The figure's rigging is memorized. The Names and Labels of bones are identical. The bones' hierarchy are identical.

Anyone have any fixes? Am I missing some step?