Airbus have got a Vibration Reporting sheet which the pilots fill in when we feel vibration. It has the pilots look at several indications and report it back to engineering which assists them in trouble shooting.
In our company one of these sheets is in the front of the tech log so that it is always at hand.
And you mention that you expect high speed to be the culprit. Do you know which speed they were flying at? The A332 vibrates a little bit at Mach 0.84 or higher.