How can you make it so only some techs appear only to certain flavors?

Flavor techs don't work that way. You have to make the techs civ-specific, by making a non-era tech and giving it to a civ or 2 then making the tech you want invisible to other civs require the non-era tech. Then if you don't want other civs to trade for the tech, make sure it's untradable as well. Flavor techs only discourage the AI :rolleyes: from learning the tech. It doesn't work either, the AI learns them all regardless. Unless it's civ-specific, and then tehy don't have it available.