Ben, unlike Jim I normally shoot sunsets similar to your settings (which sounds like manual on the first, others to follow). This lets the scene go dark like your example, which looks realistic to me. On a Sony you can choose from 3 settings to have the camera adjust to deal with sunset/rise that work well too.
The hard part of learning how you want to shoot your time lapses is that it takes so much time capturing (which is why it's nice to have 2 cameras so you can also capture single images), then lots of time in post, too to see what works, and what doesn't. More like shooting film than digital. .