How do they request a character rank then?
Not really a mechanism that I have seen to allow the Rank Request Updated for a Character.
I do believe if I recall correctly that if a character is correctly linked to an account and is set as MAIN then when you change the rank of the account it should affect that character. I would checkt the ones that didn't and make sure they are marked as Mains. If that isn't happening or my understanding of the mechanics is wrong then you need chops to way in.
Also a key thing to remeber is that Character Rank on the Site has no bearing on what the user can do. This is why they are separate. The account Rank decides the sites privileges. Take me for example. I am the Site Admin and thus that is my Rank on the site...In privilege level above my GM. But in the guild I am just an Officer and thus my character is marked that way.
There is another way to periodically fix the Rank listing player. Use GRSS and do a Guild Upload. This will update you entire guild roster on the site. Beware though as it might ask to create players that don't exist.