Making Star Wars’ Jason Ward dug into his sources regarding the Rogue One reshoots, and he got a fairly detailed (though not spoilery) breakdown of just how much there is to be done, why they need so much time, and what the mood of the crew is.
UPDATE: Writer/director Christopher McQuarrie, who worked on the script, says he is not supervising the reshoots. (MSW says he’s “helping out.”) “For any outlet to say so is not only wrong, it’s irresponsible,” he tells Slashfilm. “Gareth Edwards is a talented filmmaker who deserves the benefit of the doubt.”
MSW also found out that Scott Z. Burns did an earlier pass at the script.