All bonds issued pursuant to the provisions of sections 46-567.01 to 46-567.06 and registered by the county treasurer, provided in section 46-567.01, shall bear a certificate evidencing such registration endorsed thereon. It shall be signed by the county treasurer or a deputy and sealed with the seal of his office. All bonds, after having been registered and bearing such certificate, shall be held in every action, suit, or proceeding in which their validity is or may be brought into question prima facie valid and binding obligations of the district in accordance with their terms, notwithstanding any defects or irregularities in the proceedings for the organization of the district and the election of the directors thereof or for the authorization and issuance of such bonds or in the sale, execution, or delivery thereof.