The l:w ratio of the leaves looks somewhat low for buxifolia. In addition, the description in Flora of Australia does not mention that the pods are inflated. Apart from the pod colour. If it was originally planted, it could be anything You may need to wait till it flowers, though the Herbarium will accept specimens with pods.
These plants were planted 3 years ago as Acacia buxifolia subsp. buxifolia. I checked the internet (reputable source) which indicated the seedpods were bluish. However I will collect a live sample and photo it in more detail and add it to this sighting. I have to admit I was surprised at the blue colour. Life is full of surprises!