The battle castle is available in Mega Power, in this game, its counterpart is the Battle Department. So, for now, I have no plan to make two battle facilities since they might feel repeated somehow.
Could you please tell me more about this? If you mean challenging the Hermit Hill has nothing to do with the main storyline, then that's what it's supposed to happen, if you mean challenging it makes the story unable to continue, then please tell me more about the details or send me the save file so that I can find out what really is going on, thanks.