Restoring french polished buffet
You stated that your buffet is French Polished. French polishing is the technique of buffing in shellac mixed with alcohol and oil to a high gloss finish in many thin coats. If you attempt to sand down the differences in the slat matches, you will be in a situation to completely refinish the piece.  French polish can be easily touched up with a cloth pad and a mix of above ingredients, but refinishing from scratch using the French polish method is an art form and extremely time consuming. There is no way I know to even out the displacement of the planks without some precise sanding.   Good luck.