Also you could add agricultureBarb for barbarian minor secondary. . 'Squalor' indeed is a wrong term. What squalor can generate a mine from ancient times in a region ????? None. Probably only very very locally which is negligible.
But you can introduce unhapiness on this buidings which generate 'squalor'. Say changing 'squalor' into unhapiness.
Keep your food need, and raise substantially the wealth generated by the building, to compensate the required food. It's almost realistic/historic accurate.