I think this bonus should be changed:
"Small quality bonus when digging ball clay. (+10%)"
It used to be a good bonus, especially for hermits or small villages, giving you a decent boost to get higher q clay before you could get bone clay.
Since the addition of coade clay to the game though, it has become pretty much worthless. Ball clay only counts for a small part of the coade clay quality, and stones are going to be what boosts the coade clay q anyway, so there's really no difference between using the X quality clay you have or the X+10% q clay. At best you get a couple more q points on the final product, which is not worth a credo reward.
The quality bonus should either be increased, to make it worth it, or completely replaced with something else.