The ATSB doesn't really have the power to change things as such... They only work out what happened after someone crashes and or dies, then they, (possibly in conjunction with the coroner), make recommendations to CASA and or Government to rectify the problems.
If you have a problem with aviation safety in Melbourne directly caused by poor english speaking pilots, you need to talk to someone at your CASA field office, probably at Moorabbin. Vent your concerns and see if you get action. Believe me, most feedback does get back one way or another and sometimes it can be nasty if you are the recipient
To the gent who "turned back." You can't let other people's radio calls dictate your flight path and or intentions to land or whatever. Much of Australia's airspace doesn't require you to even have a radio. It's all about see and be seen and see and avoid. If you suspect an aircraft is nearby, have a good look out the window(s). I can't recall the number of times I've heard an aircraft quote "east" instead of "west," in fact I've probably done it myself. 8 times out of 10 you will probably never actually see the other aircraft in the CTAF / CTAF(R) anyway, unless you are actually in the circuit with them... so chill out, look out and fly safe.
"Ladies and Gentlemen this is your captain speaking. Thank you for joining us today on Qantas Flight QF46 to Tokyo. We have begun our descent into Tokyo, however I'm having trouble understanding the air traffic controllers heavy Japanese accent, so unfortunately we have to fly back to Sydney. Sorry for the inconvenience. Oh and sorry but we don't have enough fuel to make it back."