What they're seeing is the aoe marker, which is orange for enemy actions and blue for ally actions.
Generally, "area of effect" markers are not shown to the person using the action. The caster limit break displays a marker on the ground, because the action actually targets the ground and the caster needs to see it to aim it. Because the ranged limit break is centered on your target, the area is not shown - you aim it by selecting a target before using it.