Yes, they are. An example CSV line used as the source is:
[email protected],99,privilege-group-1,privilege-group-2
As I noted, the call to WPUser->add_role() succeeds, and wp_usermeta is updated to add the role name to wp_capabilities. It just doesn’t seem to do anything else, so when my template checks to see if the user has a particular role applied, the answer is always ‘no’.