The dull look is nothing more than the linseed oil coming to the surface of the shellac coat. This is normal. Let the shellac cure for a week or so then wipe down with the naphtha to remove any left over oil. Then apply a good wax to shine it up and to keep it looking nice. Now when you wipe is with naphtha just a light swipe will do and it will look a little cloudy after this. This is also normal the waxing will take care of this. Don't worry about the cloudy linseed oil until you are thru with the french polishing. The surface looks fine and you are doing it correctly you just need to do some more. The machine looks good.