It is a known issue for Australian WW1 veterans that use of the "unit" parameter with the {{The Great War}} sticker references undefined categories, and not using it adds profiles directly to mid-level "Category: Australian Army, World War I".
An example is a profile in progress for Walter Charles Josephs (Josephs-184), whom I have manually added to "Category: AIF, 43rd Australian Infantry Battalion" and using {{The Great War |branch=Australian Army |units=43rd Infantry Battalion }} has been added to "Category: Australian Army, World War I".
(Edited to remove suggestion to use branch "Australian Imperial Force" instead of "Australian Army" )
Suggest that battalion level categories renamed to match Military and War category docs, for example rename "Category: AIF, 43rd Australian Infantry Battalion" to “Category: 43rd Infantry Battalion, Australian Army, World War I" (which is sub-category of "Category: Australian Imperial Force, World War I" etc)
Then using {{The Great War |branch=Australian Army |unit=43rd Infantry Battalion }} would assign to correct category