I have been fooling around with the app, and I may have found a problem.
If you tell the app to place the home world in the habitable zone and make it a satellite. Then there will only be the one satellite, the home world. Even if it is a large gas giant that the home world is orbiting. Is that a bug or a feature?
You have sharp eyes! That is a bug - I will check it out. Your description makes it easy. You are quite correct, even where the main world is placed in the orbit of a GG as a satellite, we still need to roll for the number of satellites and there can be others.
Many thanks!