First argument-It was a translation error, Zeality settled that on like the second post and again at the end of the second page.
Black Omen-The black Omen is no more a sidequest than Magus' castle. You could have used the bucket to fight lavos before but the story continued by going to Magus' castle. After the Black Omen rose you could have ended the game through the bucket or you could go on to the next dungeon, the Black Omen. The developers wanted you to fight lavos, and thus end the story after you made your way through the Black Omen, fighting them at any other time was a decision made by the player not by the game makers.
--jp
