Have you tried "padding in circles"?

The advantage of this technique is it will allow you to "knit" together those tiny holes.

If you have enough shellac down now, I would try taking a small pad with a 1-2 pound cut of shellac, you want and will need the "alcohol" in the "polish" to soften up the shellac, and at the same time the circles you make will bring those holes together.

Once you have taken out the defects, then you can return to your normal polishing procedure.

This technique is commonly used for also removing all kinds of scratches including cross grain defects in shellac, even after the french polish pieces are in a customers home this technique will work.

It will take a little practicing to be able to do the circular motions without stopping on the surface with the pad, or you will cause a problem if you do stop.

Once you can do this you also will be able to remove scratches and other problems on old shellac finishes.

Good Luck