useTransform gives an object a place of its own, and everything made inside it is placed relative to that. The moon only knows it is 0.55 from its planet: what carries it round the sun is the box above it turning.
The same three levels drive both halves, and the only difference is what hangs off them: squares on the left, spheres on the right. The lamp is inside the sun's box, so it travels with it, and moving one line in System3D moves the whole system.