Strange time of year for the Acacia to be flowering (May). More likely to be the summer flowering implexa or falciformis than the spring flowering melanoxylon. Can Mike get the Acacia identified. I can take a look when I return. As the Dasineura are host specific this would help ID the species. The adults can also be reared out from the galls.
Leaves on the tree are somewhat variable but I have been back and it is A. implexa. I have found another plant with accessible galls so I might be able to collect some - I assume the largest galls will have the most mature insects.