Could we see an upgrade to the very young ceramics industry? I am a professional potter and have some very simple/reasonable suggestions that would make it much more realistic. I doubt any of these would require serious work and could be implemented quickly.
1. Earthenware should be able to be glazed by lead. It would consume galena, historically it was dusted onto earthenware pots and then glaze fired. This is the only way to properly waterproof earthenware, ash glazes are for stoneware or porcelain and would leak on earthenware. Tin is a colorant in glaze, tin glazed earthenware is actually a lead glaze. Interestingly, a properly made lead glaze is safe for food. So syndromes are not needed.
2. Allow for production of mugs, potters live and die on mug production, it would be a nice addition.
3. Porcelain should be more like steel. It should require at least 1 fuel, 1 kaolinite and one flux stone. Realistically it would also require sand. Real Porcelain is the combination of Kaolin, Feldspar and Silica/sand. This would probably increase its value further. In the time period DF is supposed to imitate in European history porcelain was nearly worth its weight in gold. The King of Saxony once traded a regiment of Dragoons to another King in exchange for some large porcelain vases.
4. Perhaps this isn't possible, but tin glaze is traditionally painted on with certain oxides. Perhaps glazers could put imagery onto the ceramic the way it goes on clothes or the way crafts reference history. Colours as follows: Cobaltite gives blue, Rutile gives yellow, Iron gives brown, copper gives green. Traditionally these are processed, but use of raw materials would be fine.
If these were added we would have a much more realistic ceramic industry, though I am grateful its in the game at all.