Sorry, Sylvia, still no sign of her in NSW. Julie looked in Vic and found only one who was 20 years too old to be the right one (guess this was the wrong person you found before in Vic?). Julie said there was no marriage for her, and nothing found in WA or Tas. She doesn't have the SA death cd for that time frame. Julie asked whether she ever used a middle name because there were a few Catherines, and also one convict in 1842 in Tassie.
By the way, in NSW deaths there are two male Cavendish entries: Thomas 1883 aged 53 died Liverpool, and James 1865 aged 72 died Monlamein, and two in 1839.
Sue