While the US and EU are putting up barriers to Chinese cars, Australians are buying them at record levels

Not anymore. The majority of what people drive are Japanese and Korean. However Ford along with VW and some other big EU manufacturers are also very popular. Other American manufacturers are trying hard to break in, but not doing well since American cars offer little, are overpriced, and generally suck compared to all the options from Asia next door. Ford does well because they make cars specifically for countries like us and the rest of APAC.

Without research, I would tie most of this statistic to low-budget commercial fleets and a small few people new to the country from China. I have never seen a non-Chinese person in a Chinese car unless it's some bash around work ute or truck for a penny pinching business, of which there are more and more. They are very unpopular to individuals. Even if $10K is the budget, everyone would look at the second-hand market instead.

Yes?

I don’t know how many of them are actually built in Australia, mind, in the same way that many American cars aren’t built here (or are vaguely assembled from parts built elsewhere)