This is a notice that there is a difference between "Readiness Testing" in the AVTS and actually opening the polls and voting on a real AVTS ballot. The current bug with 3.9.1, with languages is not apparent in "Readiness Testing" and is found when you actually vote a ballot.
Please make sure all testing is done with the AVTS, by voting with smartcards.
Take care,
rob (using Guy's account)