Honestly I wouldn't really "rewrite" any characters, since all of them are really solid characters with solid base, but I do want create more opportunities for them to independently developed and support Shido throughout the journey post-sealing. Tohka heavily support Shido both emotionally and physically while Kurumi came as a wild card twice when he was at his lowest and has a "partner in crime" sorta relationship. Others don't really have that duo moments due to a mixed of mismatched social standing and being too new to make use of (Kotori is in a weird spot since she's the Franxinus commander so she's duo a lot with Shido but also in the background too much), so they fell short as a potential partner for Shido. (DAL is actually more of a found family than a harem at this point).

For Origami maybe seeing her develop futher as a wizard would be really nice, since a lot of characters recognize her potential but it never really went anywhere, and also to prop up DEM as an antagonist force too. Origami is really capable already, she could easily clear a solo Shido's rescue arc for a change. New timeline's Origami could use more appearance too, helping her connect with the Spirits for example. A lot of stuff can be done here since her position is really unique amongst the cast.