I'm not sure if two FARM_INCOME building can co exist. The Church will be telling the province to produce 90% of agricultural output and the Farmland improvements will be stating 120/140/160/180%. I'm sure that only LEV1_INCOME and CATHEDRAL_INCOME are cumulative, and I'm not exactl sure of the difference between these. I've never tried the negative values for LEV1_INCOME and CATHEDRAL_INCOME, but it's worth trying.