So the Light and Dark are definitely Akane and Makoto, and the child is Chinatsu. Seems like because Chinatsu comes from the "normal" world and has entered the magical one, she'll be the key to re-assimilating magic back into the world; since the hope of normal people believing in magic again has been hinted a few times. I also wonder if "10" is a reference to a new world/realm, like Norse 9 Realms but loosely basing the idea that there are different realms, and the 10 is a new one that is possible???
Thanks for translating!!!