Basic systems are pre announced.
NS state they play Benjamised Acol, so 2♣ is 8-playing tricks (or some NT strength), and 2♦ is considered GF (usually 9+ PT, and even bigger NT).
1st board (15 secs after pre annoucement) - South opens a weak 2♦ presumably forgetting they are playing Benji.
North alerts, West asks (perhaps slightly bemused given their hand). North explains "It's our biggest bid", and West passes.
North bids 2♥. This is a relay over 2♦ awaiting developments. It does not necessarily show a bust, but denies a 5-card suit with HHxxx (min).
South passes - having been woken up to their OWN misbid by partner's alert and explanation.
If you are called to the table now what next?
Do you sanction pass by South?
Or do you review their methods over weak 2s in the majors?
For example if say 2♥ [P] 2♠ is F1, would the same apply here?
Over to you....!