Remember also the Auckland Indian and Indo-Fijian market. A couple of clubs (Mangere Utd, Otahuhu, S.A.R.) are predominately Indian,at least for the men's game. In the subcontinent countries, they go as potty over football as they do over cricket, except that their own leagues are pretty shark so they tend to follow EPL etc. I read a funny story recently how Auckland Rugby League were trying to get those communities into their sport, but they weren't keen on being jumped by large Samoan lads, so they started their own "Ethnic Rugby League" and some of them are now good enough to play with the big Pakeha and Polynesians.
I will also note that I was very impressed at the several little knots of young East Asian people, male and female, at the Eden Park game.
But I think the issue is that YF culture is quite based on Brit and, to a lesser extent, other Euro fandom, so I can see why other ethnicities would not find it easy to get involved.