After using the add new comment api, I only manage to add comment as the owner of the board. How to set the comment creator as the guest account or other member account? Please help
Currently it’s not possible to create comments on Trello cards on behalf of other people. Comments are always ‘owned’ by the person making them, which in your case is the user account you used when calling the endpoint.
In this respect, the REST API is identical to the GUI.