It was only Shaikh Mahmood Shaltoot who as head of department a center at al-Azhar by the name of "Dar al-Taqreeb al-Madhahib al-Islamiyyah" which translates into "Centre for bringing together the various Islamic schools of a group of Sunni and Shia scholars formed thought" issued that fatwa on 6 July 1959.
It is not the official Fatwa of AL Jamiah Al Azhar recognising the Jafaariyah school of thought. Other recognised authorities disassociated themselves from this Fatwa.
Sunnis do not recognise the Jafaariyah school of thought officially.
It would be interesting to know why the Shia Ayatollahs did not reciprocate in kind and recognise the four schools of thought.