We cannot know how many, if any, of that hypothetical 11 voted No on the basis of the UK party leaders’ “vow”. That is fruitless speculation.
But clearly it is essential that the vow is now delivered in full and promptly. There may well be good arguments for constitutional reform for England – I believe there are – and indeed for the UK as a whole.
But they were not mentioned in the vow, and its implementation should not be made hostage in any way to progress on those other issues.