They need to weigh in on some of these questions, otherwise I'm just going to assume they say "crikey" and "good on yer" and "shrimp on the barbie" all the time.
Well, we have @jimsug and @AndrewGrimm among our regular contributors, looking at self-reported locations visible on the Users tab.
If the concern is about global representation of Englishes, I am more concerned about our failure to recruit participants (either questioners or answerers) from the Philippines, the Caribbean, and sub-Saharan Africa (esp. South Africa, Nigeria, and Kenya). For that matter, we don't seem to have any Irish among the top 100 participants (by reputation points) either.
We do weigh in on questions, but we avoid referring to throwing prawns on the barbie because it is rarely relevant to the question.
We (I) also tend not to use "In Australia we use the word like this ..." very often because generally the British use English the same as us, and it's better to link to the OED than the (much less reputable and less free) Macquarie Dictionary that we have down under.
Also, we tend to get moderated to oblivion, due to our tendency to drop a certain word quite casually that is fine amongst mates, but shocks other people.