Australia, no screens.
EW play Standard, short club.
This is a new partnership.
All 4 are average club players.
Before acting, South asks about 2♣ and is told "6-10"
EW have a rudimentary system card but this is not listed.
At the end of the play, after the director is called by South, West offers:
"We are a new partnership. I usually play Acol. I thought that after a short club, my 2♣ showed 10+ points, forcing."
They (maintain they) did not agree to play inverted minor raises.
How do you rule?