So what is the point I'm getting at? Simply put the worlds that exist within grains of sand should in turn also have worlds within them, leading to a recursion effect.
I have three reasons for my logic that I'll just briefly summarize.
1. Firstly
Chilicosm & Buddha-Realm's statement says "A grain of sand", not a grain of sand in this world, just a grain of sand. It's a very broad statement referring to every grain of sand pretty clearly. On top of that, it states clearly that a Buddha's entire realm exists within a grain of sand. That would also have to include the one in the Main JTTW World.
2. It's also stated that
Buddhas exist in every world. That would have to include the lower worlds as well, in which the Buddhas within those lower worlds would also have their own realms.
3. If the Great Way scans do indeed mean it's responsible for these recursions of larger things such as Worlds, Buddha-Realms, Mountains, and Oceans being within smaller things, then why would it not affect the lower worlds within the Universe it already encompasses?