Remember, it's the opposing team who have said that Aria is acting as Volante, not Aria. As far as I can see Volante's also make attacking runs which Haru is incapable of - this may lead to the opposing team thinking she's going to make a run as a Volante and then her throwing them off with just a pass.
i was thinking "damn, i've only heard volante be commonly used in fm..." and i go here and it's literally first thing i see is FM tactic discussion
also gotta say the terminology in this manga has been on-point (didn't expect inverted fullbacks at all lol) but i can tell the author got inspiration from FM because really only FM players use AM(L) to describe a left winger lol