It'd be nice if we stayed Australian in terminology as well. We normally use "First World War", "the Great War", or "World War One". It's not normally an Australian thing to use World War I unless we use the initialism WWI.
Also, my grandfather, his brothers and his cousin all signed up to the Australian Imperial Force, NOT 1st Australian Imperial Force, yet profiles have been changed to the latter without so much as a word.
I guess some of us are puzzled and frustrated.