ETRTO is an ISO standard it's world wide.
Unless you've found an Australian bike tyre manufacturing plant, you're buying imported tyres, therefore they'll be stamped with ETRTO numbers. (maybe freaking tiny sometimes but they'll be there).

Couple of Australian bike companies explaining tyre sizing for you.

https://adelaidebikeworkshop.files.w...tyre-sizes.pdf
http://www.moruyabicycles.com.au/con...-uk/d1097.html

Just go to the schwalbe site https://www.schwalbe.com/ when you search for tyres it gives you an option to sort by ETRTO sizes then you can see exactly what choices you have, find something you like, look at the product page.. and it'll give you the sizing in English, French, German or what takes your fancy.

Depending who I talk to my 662 tyres are 700C, 29", 28", or 27" at the end of the day if the tyre is stamped with 622 I know it'll fit my rim, no fuss.