that is correct. Combined Arms attacks share the fate of the cavalry repulse.
Any artillery that declares a combined arms attack with a cavalry unit that is fighting an enemy infantry unit in square can lose its combined arms attack. This will happen if the infantry unit in square, when fighting first, either eliminates or causes the cavalry unit to bounce retreat. The artillery unit’s combined arms battle dice are lost, because the cavalry attack is repulsed before the cavalry unit could make the melee attack.
www.ccnapoleonics.net/Rules/Base-Game/06...ics-and-actions.html