As is, some recipes benefit from having a blend of flours(Surzhyk), rather than 100% one flour or another(similar to spices and pickles, however the matrices or math works under the hood). The ability to preblend flour would be nice, to reduce the amount of keypresses/botting necessary to craft recipes with a mix of flour. Perhaps Surzhyk could only be initially made in the inventory(right click flour stack onto flour stack), and afterwards, barrels would accept multiple flour types and blend accordingly. This way clicking a barrel of pure flour onto another pure flour does not create Surzhyk, it can only be done very deliberately. Surzhyk(Bread) could also be added as a recipe, requiring blended flours rather than pure. Perhaps that should require fixed quanta of each flour type rather than free for all flour blending.
To be clear, it's not as if adding the ability to preblend flour makes recipes and FEP gains more complicated. Idealised recipes already benefit from whatever blend of flour, this simply makes it more accessible to make recipes from blended flour when appropriate. If arbitrary blends of ingredients are odious and complicated(IE 96% juniper 4% tansy or whatever), that's a problem to be remedied with the underlying FEP math system, not the ability to more easily create the blends favoured by the underlying FEP system.