They really should start using real names instead of numbers. There's just no efficiency in using it not to mention it coincides with actual number when say, trying to point out firing angle or direction. Yelling "Oh-four", "Four", or maybe the korean pronunciation is just not it bruh. Heck if it's too much just use codenames, or numbers pronunciation but in different languages (Hana, Zwei, Tres, Shi, etc.)
I mean isn't the main story also about humanizing these bunch of living weapons? Having them using real names is a good way to start it off.