Melanie, I know it's all caps, but I'm lazy sometimes. If they are merged then, it should be [[Category:ANZACS, World War I]] I was focusing on the war part of the name.
I do not think it needs a review for the name of the war. M&W decided that already (see the link I provided.) It makes no sense to have different countries around the globe calling a war by several different names, and categories would be all over the place and we'd hear "I can't find where to put my great-grandfather who served in that war that took place between 1914 and 1919."
The project can have a name which differs from the category. The category is simply to group the persons from around the globe who fought/served/died in that specific war. People around the globe called it several different things, but for there to be a grouping of all who served, WikiTreers agreed on World War I through, I'm sure, a collaboration. (I wasn't around for that, but it seems logical to believe it happened that way.)