Yes, I think it looks realistic for what it is. You are graphing Watt-Hours (Wh) which is a unit of energy. Typically, I would look at Watts, a unit of power, for something like this. If you plot both Wh and Watts on the same graph, they will look identical, but the difference is that the units in the scale will be something that I can relate to.
For example, the larger increase around 22:00 is an increase of about 40 Wh. Your plot is showing 2 minute intervals, so that increase represents something that uses 40Wh in 2 minutes. That’s hard to understand.
(40 Wh / 2 min) x (60 min / h) = about 1,200 Watts. I understand 1,200W. That a fairly high power 120V load. We know it’s 120V because the other leg doesn’t change. The increase 2 hours before appears to be a 240V load as it shows on both legs.
So give Watts a try, it may be easier to understand. If you want to know the total Wh for that 24 Hour period, you can look at the statistics below the graph that will show the total Wh of a Watts plot line.
No, it is not accurate. In fact, some 120V circuits don’t have a neutral. Something like a well-pump or hot-water heater does not typically have a neutral. You can read about it in the documentation here.