Those well versed with Australian accents are welcome to check out the latest tuning effort at https://eurpod.com/en_au_tuning.zip - this includes a much more improved pack that solves the 3 phonemes missing from the version initially there. This was part of the SpeechPlayer work in 2016, so whoever tuned these phonemes now gets to have their work live on.
@Tamasg what folder do I put them in?
@ginsenshi oh, here's the exact thing to put in your run dialog:
%appdata%\nvda\addons\tgSpeechBox\synthDrivers\tgSpeechBox\packs
Copy everything from that zip (as is) and say yes to replacing.