I'm not sure but i guess that Kokuku didn't do his homework on Angelica like she did on him. At this point, wouldn't it be a known fact that the war with the demons is over because of the marriage? And on the same note, wouldn't it be widely known that she is the daughter of the wife and by default she is technically the demon princess and hero at the same time? She is actually doing both of her roles quite well if you ask me.