I am using BuddyPress 1.5.5 with Events Manager 5.2.9.
The events manager bookings management correctly shows the user who booked the event. However on the BuddyPress activity stream, it shows Non-registered User is attending event, even for my own bookings.
The only customization I did for my site is to use wp_set_current_user to login the user instead of using the wordpress default login page because of single sign-on.
This is the code section dealing with the login.
wp_set_current_user($user_id, $user_login); wp_set_auth_cookie($user_id); do_action('wp_login', $user_login); //bp_core_redirect is required to fix the login problem where user name is not setup correctly in the first page. bp_core_redirect(get_option('siteurl').$_SERVER['REQUEST_URI']);