Hi y not,
Is this the book you mentioned? (here). Thank for your mention to the book, I found places in the book were mentioned by you. But it’s lack concrete evidences from both Tipitaka and sciences. The number of “world systems” (10^102) which a single Sata-Sahashri brahma governs is too much, exceeds the number of particles in the observable universe itself, if this is true it will mean a Buddha Sansana governs the whole universe and more, not just 1000 star systems, but I need more research though.