"You are among us."
Translation:Jesteście wśród nas.
Of course we are using both. The honorary „pan” is obvious choice in formal situations, but we still need informal you for normal situations (because unless you are a cliched gentleman, you wouldn't call your best friend „pan”). There's nothing extraordinary on its own in either form.
I'm not surprised the course creators forgot about the formal form at first, though. With English not really having polite form, it may be easy to forget about it when creating a list of allowed translations.