Responses
I don't think the prophecy was faked, just based on how they said in the early chapters that Caius was removed from the Titan's life cycle because of the prophecy. I think the other Titans were also having trouble recognizing him because of it. I'm hoping that the prophecy was real, otherwise OOOFF, wtf.
Could it be that the prophecy is fabricated and Sefal is making the king ill, and that they never wanted Caius to become king in the first place?