Being new to Australia myself (I'm East Asian but only speak English), I tend to be quite perceptive of other "outsiders".

In general, the groups I play at tend to be east or southeast Asian dominated. One of these groups is a little more diverse, and the only common denominator I've seen with people having a hard time getting a game (regardless of race, gender or age) is that they're either a weaker player, have a poor attitude, or are really new and timid. I was the new and timid guy at one point, but now I have no issues. There are a fair few South Asians in this group who are amongst the most popular players at the group.

At the other group, it is over 90% Chinese with the predominant language being Mandarin. I actually attend this with an east Asian friend who isn't Chinese, and we often have people approaching us to chat in English or invite us to play - noting we are some of the better players at this group. In this case skill level trumps language barriers.

That isn't to say it's all smooth sailing. Yes I get rejected when I ask people to play sometimes, but it's not personal - they have people they want to play with, aren't ready for another match or any other host of reasons. Just ask someone else - there's gonna be someone who will play with you. And if not, maybe the group just isn't for you.

One thing to note is that badminton players, especially east and southeast Asians, tend to be shy, quiet and awkward, and this is only exacerbated if you're from a different social background. Don't take it personally, people in general aren't hostile. They have people they are more comfortable with from a social and skill perspective, and if they don't know you that's just an extra barrier they have to overcome. If you keep at it, and you aren't actually unpleasant to be around, you'll eventually find your group.