I don't believe it. Pointing ability refers to the angle of the relative wind
on the sails
when sailing to windward, and any modification to the keel
would be to reduce the angle of leeway and that's not the same thing. There have been many mods to the keel that actually do that like having articulating rudders at the fwd and aft edges of the keel, the triangular athwart-ship cross section keel such that the windward side of the keel when heeled produces a greater airfoil curve in the horizontal plane than the leeward side, and the winglets which increase your draft
when heeled and because of a greater airfoil shape on the bottom of the wings, they are supposed to give the boat a little lift
to windward which in actuality reduces slip or leeway.
Any of these modifications to the keel would reduce leeway by there design but because of their increased frontal area resistance,and increased wetted surface resistance would slow the boat slightly which would cause a corresponding increase in the leeway. So I don't think there is any gain, and if I am wrong it would be measured in fractions of a degree and certainly not 10 points.
If the winglets in question were added as aftermarket add ons, then the increase in draft
and ballast would make the boat stand straighter, and that would have a definite affect on pointing ability, but 10 points is still excessive.