Page 6 "I'm not kidding" but coming out of Uncles mouth, maybe "You're not kidding" would read better?
Page 8, Opal's last bubble. "Escorting me until here is fine" I wonder if this has also been translated too literally, She's thanking him for his help until now.
Page 9, Uncles first bubble "Don't make a move until you get there!" Until who gets where?
I could probably fake being an english teacher better than I could fake reading Japanese though