Katarina I have submitted a quarantine concern report to quarantine@dpi.nsw.gov.au will await a reply, as far as I can tell Macrosteles has not yet been recorded in Australia.
NSW DPI Biosecurity Surveillance got back with teh following "I can definitely say based on the wing venation that the specimen in the photo is not Macrosteles. It is Cicadellidae: Deltocephalinae. Most likely a native Australian species, possibly Limotettix incertus, but without seeing and dissecting the actual specimen I can't go with certainty to genus or species level."
I would go with Limotettix incertus. It's a close fit with images of that species in ALA, and the records show it widely distributed in ACT, NSW, Vic and Tas. Neither of the two other species of Limotettix is listed as occurring in ACT, and neither is common.