Can we print the folio / invoice in another language or otherwise change the words on the invoice printout to words of our choice?

Yes, you can revise all the wording on the folio/invoice, reservation form and guest check-in form.

From the main menu, select: Utilities | Site Setup | Reservations | Reservation Form Tags or ..| Check-in Form Tags or ..| Folio Tags.

Also, use this option to revise the wording of the folio / invoice to meet the requirements in Australia. Change the word folio to Tax Invoice as required.