What data is missing when copying a Trello board compared to exporting its JSON for rollback?

Teams preparing for high‑risk board changes need a reliable snapshot that can be used to roll back to a known state if the change introduces problems.

Because Trello is a cloud‑only service, the only user‑controlled options are creating a board copy or downloading a board‑level JSON export. Documentation confirms that a copy duplicates lists, cards, descriptions and labels, but it does not guarantee preservation of comments, activity history, attachment fidelity, checklist items or custom fields, and workspace limits may block the copy operation. The JSON export captures cards, lists and metadata at a point in time, yet Trello does not provide a documented one‑click restore path from that file, and it is unclear whether all board elements are included in the export.

Which specific board elements (comments, activity history, attachments, checklists, custom fields) are retained in a copied board? Does the JSON export contain all necessary data to reconstruct a board’s state, and is there a documented method to import it back into Trello?