If any real estate mortgage given prior to January 1, 1943, was foreclosed in any action or proceeding by a foreign executor, administrator, or guardian, such foreclosure, after six months from and after the date this code takes effect, may not be set aside by reason of the appointment of a resident executor, administrator, or guardian, or by reason of the failure of any such foreign executor, administrator, or guardian to file an authenticated copy of the person‘s appointment as such executor, administrator, or guardian, in the office of the clerk of the district court, or to record such copy in the office of the recorder of the county in which the action or proceeding to foreclose such mortgage was commenced, if a certified copy of such appointment heretofore has been recorded in such county, and if in the action or proceeding to foreclose such mortgage a sheriff’s certificate has been issued prior to January 1, 1943.