Other than glazing, pottery works fine in kobold camp. There is no drying needed for the bolds, just shape and fire it up and you're done. When you shape pottery for the bolds they give you greenware stuff, I think it's listed as tool_whatever_fake in one of the raws. You could try copy the pottery system over from the bolds to remove the drying part of the pottery making process although the drying reactions are supposed to be done automatically I think. Haven't played the dwarves or orcs lately so I wouldn't know.
Edit: After looking through the raws, Orcs make clay stuff from the goblin muckraker shanty building. It seems to have reactions to directly make clay items, it shapes AND fires them up in one quick and clean reaction, all you need is the clay/fire clay and fuel.
2nd Edit: Further inspection into the raws lead me to believe only the dwarves have the drying reactions or atleast their pottery stuff needs to be dried before firing them up.
3rd Edit: I think the standardization options is what causing the problem with glazing? Instead of making powders, you could edit the kiln to accept ash and etc directly and apply the glaze from there. Downside would be that it would use the entire material for the reaction. You would also have to add the glazes in inorganic_other.