Thanks for getting back to me on this.
I found that the new_user_approve_user_approved action passes along a user Object so I didn’t have to establish a new one. The code that worked for me is slightly different than what I posted:
add_action( 'new_user_approve_user_approved', 'change_user_confirmed_group');
function change_user_confirmed_group( $user ) {
$user_role = $user->roles[0];
$user_id = $user->ID;
...assign group to user based on role
}