Have they been bred at all here?
No, Cheetah cubs have never been bred at Australia Zoo. To promote breeding, Cheetah require large spaces; accomodation away from other big cats; and a selection of males for the female to choose from.
Australia Zoo can provide the females with multiple males to choose from; but they are housed in close proximity to their Sumatran tigers (compare with Orana, where the Cheetah are housed at the opposite end of the park to the lions and tigers); and their individual exhibits aren’t huge.
This isn’t to say they won’t breed if all these factors are satisfied; but zoo’s whose facilities can meet this criteria experience greater success.