If you look at my specimen it has a semicircular mark on the inner margin of the forewing(about half way, the marks from both forewings are side by side where they cover the abdomen), this mark can be seen on all examples of various species of Shargacucullia on this BOLD site https://v3.boldsystems.org/index.php/Taxbrowser_Taxonpage?taxid=196769 I have not found images of all the species of Shargacucullia
Yes. looking at your references there are strong similarities with Shargacucullia lychnitis and Shargacucullia (genus), including thhe forewing margin shape, and hints of the forewing halfway marks you allude to, Also other Shargacucullia species show dark hindwings.
The other path is a species introduced to Australia (by CSIRO) for biological weed control. I have been chasing these up but not found reference to any Cuculliinae as yet.
The Neogalea sunia Catabena Moth (Cucullinae) was deliberately introduced from the USA to control Lantana https://lepidoptera.butterflyhouse.com.au/cucu/sunia.html
Roger Kendrick has suggested Stictopterinae which fits better with the Australian fauna. I still have not found a match but believe it fits within this subfamily