Translate the following English sentence to French:
"Secondly, the irregularities identified by the Court of Auditors refer mainly to errors in relation to proof of expenditure which are signed by Member States, and for which they are responsible."
Deuxièmement, les irrégularités constatées par la Cour des comptes portent essentiellement sur des erreurs de certification des dépenses dont sont responsables les États membres.