I wish we got to see the Prince's fate too.
As for why she can clean: she probably did it in secret in her home too (if her parents knew she would have been punished. And since her parents are definitely doing shady things, they must dislike bright open air (psychological: if you have things to hide you have a tendency to live in closed environment)). Hence, why he parents got possessed when she left, since she stopped exorcising the mansion. There is definitely a need for the story to have more chapters, explaining how she did in her family's home, about the curse, etc.
It could be a short serie of 2-3 volumes and I would gladly read it.