Thanks for the detailed info! Just to clarify, is 1Password spitting out single or multiple exports in this case? Have you already checked out the Condition a Bitwarden .csv or .json | Bitwarden Help & Support doc which allows for bulk edit of csv file? I also created a post here Select Multiple entries and applicable actions - #27 which may be helpful.
It sounds like you successfully imported items into your individual vault and are now looking to have several shared collections in the organization vault with different permissions/access?
I look forward to hearing additional details and you can also contact the official support anytime at Get in Touch | Bitwarden if additional assistance is required.