I wasn't as clear as I should have been - a "building" fully constructed on one planet, often with a fluff description that it would apply to that one planet, then having a full effect on another planet in the system once it's colonized, doesn't make sense to me. Having "buildings" that from the outset affect the entire system isn't that much of an issue, just that it needs to be clear that you're paying for a system-wide "building". There should probably be a higher cost for system-wide "buildings" when the system is bigger, even after the initial construction is completed, requiring upgrades to be purchased/built to affect more. But most "buildings" on planets should affect that planet only, even in a multi-planet system - this is the opposite of Endless Space and ES2, which only had a handful of "buildings" at purely the planetary level.