Pharaoh 90 is from the Tau Star System which is an alternate dimension. Pharaoh 90 comes from the cauldron. This disproves that the cauldron only governs the galaxy.
Queen Nehellenia is from another alternate dimension as well, the dark world, or the shadow of the new moon.
Also, within Sagittarius Alpha Star is a graveyard. Each grave represents a fallen being, star, planet, etc. There is also unending procession of dying embers of fallen stars. These dying embers emerge from the graves and take flight.
For the procession to be never ending, the graveyard is never ending. For you interpretation to work, there must be a never ending amount of planets and stars in the galaxy. Remember, when things die, their star seeds return to the galaxy cauldron.
My friend, you have confused me here. Sailor Moon is poetic so you can’t “take it literally” but also you want to take the words, “Edge of Spacetime” literally? This comes across and picking choosing what you want to take literally and what you don’t want to metaphorically.
I take it literally because the cauldron literally creates everything and is the source of all beings, objects, powers, etc. it creates celestial histories, destinies, and is the system that govern the stars. There is no reason to take it as only metaphorical. Was it metaphorical when Guardian Cosmos said this is the birth places of stars? Why would one half of the sentence be literal and the second half metaphorical?
This is a verse where stars are alive and can take human form. There’s no reason we must believe supernatural elements are not in fact supernatural.