Right I have some clarity on what was going on with these Rebel Pilots going to Jedha it’s not an attack and it’s not a diversion.

Seen in the IMAX trailer Dodonna and Bail talking and giving a briefing I think in an expanded version of the plot. The Rebel x-wing Pilots were to Land and inspect The defected Pilots deserted Transport (Very Dangerous!). Jyn and Cassian’s mission was to gather more intelligence From this point from another location a connection was made between finding out the identity of the pilot that had actually defected from the Empire was called Bodhi Rook this information was relayed to Jyn and Cassian by the x-wing pilots at the deserted transport. Also from intelligence via Cassian Bodhi Rooks sister was identified as living in Jedha city and the plan to go to Jedha City was then formed.

The x-wing pilots however whilst grounded get attacked and arrested at Bodhi Rooks deserted imperial transport.

Jyn and Cassian then set off for Jedha City with the Pilgrims and are in search of Bodhi Rooks Sister. So as to lead them to or find out the whereabouts of Bodhi Rook. Little do they know that Saw already has Bodhi Rook in his custody.

It’s very much something along these lines… It’s all about the mystery Pilot that has secret information. And finding out who he is and where he is. And the only link is his deserted transport on Jedha.

http://starwars.wikia.com/wiki/Bodhi_Rook’s_sister

Don’t rule out this plot point simply being done over com’s chatter from the U-wing. We don’t need to see anything only that the pilots name was given over the Radio. We would have stayed with Jyn and Cassian.

Also if there was any doubt the Empire already had Bodhi Rooks sister in their custody. There was no chance of finding her at that point.