Raymott!
No, I have no data suggesting a difference in the way that the Britons and Australians would use singular/plural for collective noun interchangably. I reckon that since AusEng has been developing for so long in (sort of) separation from the BrEng, there would be definitely such differences. The country's history - who (was) originally settled there - may also play some role development and shaping of AusEng.
Once I find such differences in corpus data, I'll to try analyse them from various angles and explain why and, more importantly, how these differences have arisen. Maybe, as Tdol noted, it would be also of some interest to analyse how people speak, and to include this data into analysis.
Thank you a lot for the resources you provided!![]()