((5))A decision on a matter entrusted by paragraph (3) or (4) of this article to the court specified in article 6 shall be subject to no appeal. The court, in appointing an arbitrator, shall have due regard to any qualifications required of the arbitrator by the agreement of the parties and to such considerations as are likely to secure the appointment of an independent and impartial arbitrator and, in the case of a sole or third arbitrator, shall take into account as well the advisability of appointing an arbitrator of a nationality other than those of the parties.