At the very moment reviving conquered civilizations to life is more of a "fancy thing you do because you're bored" than "good thing to mess with your rivals". Liberated civs, especially those conquered earlier in the game, got a huge technological backwardness (buying knights in info era). Along with having no military and having no economy they're literally unable to put a fight against barbarians, not to mention standing against whole world which for some reason quits current wars and decides to gank them. I'd like to suggest either giving RECALLER an option to boost RECALLED with known technologies, or automatically push freshly-independed at similar level of technology to other civilizations (this is self-balanced by lack of economy, it will take some time for "new" civ to catch up with the rest of the world) or at least give them temporary boost to military production. This suggestion is backed by written history - it does know many cases of countries gaining independence after many years, up from decades to millenias, but not a single case of sending mass produced pikemen against tanks in modern era. Thank you for reading.