Wouldn't it be a good idea to just mod away one of the two grain resources?
Preferrably the one in the Alexandria province. I never liked the idea that the grain resources always come in pairs of two, Carthage - Syracuse, Egypt - Egypt, Chrimea - That scythia province. It makes in my opinion a too huge food surplus in said and nearby provinces. Alternatively you could mod so that each grain only gives a bonus of +0.5% or whatever instead of +1.5% which in total gives a staggering +3% food surplus. I don't know but I guess it would be enough just removing some of the grain lines in the resource text file. Can anyone confirm that?