Hi Emma,
In case you haven’t resolved this already, I believe the NIIA manage ATSIC caveats now. Here’s their caveat web page https://www.niaa.gov.au/indigenous-affairs/land-and-housing/commonwealth-caveated-property
NIIA’s Tamworth office is closest to you, contact details:
Kathy Rowe
Eastern NSW | Tamworth Regional Office
National Indigenous Australians Agency
p. (02) 5712 9001 m. 0412384174
e. kathy.rowe@official.niaa.gov.au
If you cant get hold of Kathy, Anne Sattler is very helpful too:
Anne Sattler
Eastern NSW Region
National Indigenous Australians Agency
p. (02) 4913 7905 m. 0423 609 754
I hope this saves you time.
Best wishes, Richard