Wake turbulence ?
When i did my formation endorsement in a trike i couldn't believe the wake turbulence from the trike in front, almost rolled end for end one time.
Got the endorsement and never did it again in the trikes because they are just so upset by wake from leading aircraft and it extends way out to the sides much further than expected, real learning experience.
Looks like the Townsville accident 'may' have been the same thing ??
Formation flying is not easy in aircraft from the bottom end of town.