If you have the time, skill and tools, anything is possible, but we're floating away from buffing vs polishing original question(s), let's agree that is personal preference and restoration of cases can take different processes, based on user experience. Whatever works to achieve desired results.
I agree with RCDesign, lapping is the way to go on a square case, I don't have the setup to accomplish this, so by hand with Foredom and different buffs/rouge, I try to accomplish a presentable finish, like you said, not perfect, but close enough.