Pretty sure the separatists have killed civilians themselves. If they are dumb enough to shoot down a civilian airplane, admit it and than later accuse the Ukrainian military for it and basically bribe local old ladies as witnesses of it, sure as hell they caused some shit too. Again noone cant prove a damn thing. Every civilian the separatists kill by accident they can just easly blame Kiev for.
Honestly thou, why would Ukrainian army bomb civilians on purpose? I mean theres no need for it. The russian explanation "cuz they are na zis" isnt sufficent. The separatists have much more reason to murder civilians on purpose. Think about it. If they were some twisted desperate sick mofos, it be pretty easy to massacre civilians and blame it on the government. Amist the chaos it would work quite well.