RSVP export - add extra information fields

I would like to add extra information to the RSVP CSV export of a Event.

I've found the export code in
events-and-bookings/lib/class_eab_exporter.php

and i want to add the buddypress group the user is registered in so i can sort them later by group. I tried the bp_group_is_member() but i can't get this working.

I've tried other ways like to install the plugin Export User Data and WP Users Exporter but there i can't find the Event+ fields and/or the buddypress group fields.

Is there a way to realize this option?