I'm looking at getting Skydemon but I notice that the New Zealand chart is missing airspace - like the G class airspace at Ardmore airport.
Is this because the chart isn't completed yet?
It means the integrity of the whole system is flawed.
What is the plan here?

In SkyDemon all airspace is implicitly class G if there is no presence of any controlled airspace. You should not expect to see "areas" of class G defined or depicted.