I am trying to assist and your backups can be suspect I mean we cant say the data is realiable.
For me to answer which action I laid out for you to try to resolve your issue I need my question answered.
These users whom say there gallery username is different than there vb
name when they view there photos etc are the photo's theirs or someone else's?
We need to know whether its a userid or a username issue. All par for the course when we are talking username changes or integration switching.