Admittedly this is a minor point but this is not how meltdowns work. What if all resource output in that particular city is reduced, to simulate reduced power output? Turning off the power plant completely seems too major of an effect, so this may be a workaround. I like these ideas otherwise though
They are probably just in an opposite timezone from you. There's also no war slot filling here as judging from the war timelines they are attacking you pretty consistently