The demon beasts' main reason for looking for the twins was obviously the formations. Although they weren't very versed in formations, they still used many of them in their territory. It's just that their formations were usually mixed with some kind of bloodline requirements. But then again, these bloodline requirements also helped keep things safe on their side. With that being said, they at least understood just how important the Circuitry Formations were. If the demon beasts could incorporate them into their own formations, perhaps they would be able to match or even surpass the formations used by the humanoids, spirits, devils, and angels.