The story will get boring if it goes down the route of: Christopher, still charmed, puts Sylvie in a position where she cannot fight the dark force and Edgar has to save her, romance ensues (at a very slow pace), and Christopher is 'punished'.
This is really their only move, hope they have 100% from everyone to cut trade with Tadashi. Of course, this will fail, due to it being difficult to get people to drop luxuries once they have them, the Holy Kingdom will realise that they do not have any stakes in this ordeal.