Tobacco harvests don't actually result in... you know... Tobacco. Searched the script files. There is a mistake in the crops.edb file Line 852 reads: outputCommodity = "crate_of_tobacco_leaves", it should read (I believe) outputCommodity = "bushel_of_tobacco_leaf", EDIT: Tried making the change to outputCommodity - still no good. Missing something here...
It is the right solution but you have to demolish the farm and build it fresh, because farm.go takes cropdata from its internal state at state.cropData = EntityDB[ state.cropEntityName ]