We are not told what Bar-Jesus did exactly. Presumably he would speak up to either challenge what Paul is saying or try to explain why it was foolish to listen to him and believe his message. Since his own livelihood depends on the proconsul rejecting the gospel he would have made a significant effort.1
8 Mais Elymas, le magicien car c'est ce que signifie son nom leur faisait opposition, cherchant à détourner de la foi le proconsul.