Is there a way to set up an Australian English language? We all hate US English

How can I set up an Australian English language or set up a custom one? 


As far as I can make out, there are TWO locations:

  1. General/Language - where you set the *GUI* language (I think)

  2. General/Spellchecker /Download Dictionaries - where you set the active language for messages - and Aussie English is listed there. I suspect that’s the one you’re after >.