Redoing orders does not matter unless you score higher on them. The characters overall rank depends only on how well you do on their specific orders throughout all the days, the ranks for each day are averaging out the scores every character got on that specific day.
At this point the interaction between the gallery, the levels, and the weights on any particular save file depends on what scores you got on which levels in what order during which version and how many times you visited the gallery in between, which is an unfortunate consequence of me fixing these things over time while people are playing.
That being said, starting from a fresh save is the only thing I can bug test on since I don't have everyone's save files, but as long as you score majority S rank on a character's orders throughout all the days you should be able to see all their weight stages in the gallery.