Was anyone able to answer your question about Greek clubs down under Dutch? If not I'd be happy to list them
EDIT:
Had some spare time so I've whipped this up.
In Australia's national competition that ran from 1977 to 2004 (National Soccer League), most clubs were of ethnic background, Greek, Italian, Croatian, Hungarian etc. Greek clubs that played in this competition came from the cities of, Melbourne (where you have the largest Greek population outside of cities Athens and Thessaloniki) Sydney and Adelaide.
Melbourne:
South Melbourne Hellas Est 1959- Still the countries most successful ever club. 4X NSL Champions, 1 Oceanic Champions League Title and an appearance in the FIFA Club World Cup (where they played Manchester United).
Heidelberg United Est 1958- Formed by Makedones mostly from Florina, 2X NSL runner's up
Sydney:
Sydney Olympic Est 1957 - 2x NSL Champions
Adelaide:
West Adelaide Hellas Est 1962 - 1 NSL championship
The folding of the NSL started up a new national league (The A League) where clubs of ethnic background were not permitted (at least the more stigmatised ethnicities like Greeks, Italians and Croatians) entry and mostly brand new clubs were born. The Greek clubs mentioned have since played in their domestic leagues in the states of Victoria (Melbourne), New South Wales (Sydney) and South Australia (Adelaide).
Seeing as the A League does not have a second tier competition the domestic league, the NPL (National Premier League) is run within each of Australia's states and territories. This is where you'll find many more Greek clubs like the one which you saw in Darwin Olympic who play in the Northern Territory. Domestically clubs and players of ethnic background still dominate, this is why you see players with Greek, Italian, Croatian last names running around in Australian shirts. However not as many as before when the NSL was running.
The NPL is a semi-professional level however the big Greek clubs like South Melbourne and West Adelaide still have aspirations of gaining entry into the A League. The two states who's NPL are the nation's strongest in my opinion would be New South Wales and Victoria. I'll now quickly list as many Greek NPL clubs as I know, there are many, many more clubs playing in several other competitions below the NPL also.
Victoria:
Bentleigh Greens (Cypriot)
Northcote City
Oakleigh Cannons
Port Melbourne
South Melbourne
Heidelberg
New South Wales:
Sydney Olympic
Hamilton Olympic
South Australia:
Adelaide Comets
Adelaide Olympic
West Adelaide Hellas
Adelaide Cobras (Cypriot, play in another division below)
Western Australia:
Floreat Athena
Northern Territory:
Darwin Olympic
Hellenic Athletic
Queensland:
Olympic FC
ACT:
Canberra Olympic
Tasmania:
Olympia FC