But when faced with a stretch/development/legacy programme, where you're being told that you have to re-use old components and minimize (costly) redesign whereever possible, it's very easy to end up with the cg in the "wrong place" - because the traditional fix at initial design is to move the wing, so that the cg is in the right place, and moving the wing on an existing design is not cheap.
A competent and honest supplier - having discovered thru analysis the potential problems, would have explained them at the proposal stage.
But this, of course, would have opened the door to the new airframe option, and likely meant a lost order for BAE.
As they evidently didn't explain, they ought to absorb the cost, as they would have to if they dropped the ball in a commercial situation.