Roman Auxilia Equipment

I was wondering why the EB team decided to depict the Augustan auxilia cohorts as heavy spearmen or spearmen/swordsmen.

From my reading on the subject I was under the impression that the auxilia were generally equipped very similarly to the legionaries, with mail armour, javelins, (though not pila) swords and shields Some probably fought as skirmishers, though I don't think there's much evidence about how those were equipped.

Vanilla total-war depicts them as spearmen, and to be sure they fulfil a more useful tactical niche in the total war engine this way, but neither of those reasons really seem to fit the EB team's general approach.

Then again, the auxilia units only appear towards the very end of the game so maybe it was considered less than essential to depict them accurately?

Or is there actual evidence that the earliest auxilia cohorts actually fought as spearmen?

Either way I'd be interested in knowing.