So it turns out that 4.5 also saves records in civicrm_mailing_group with entity_table='civicrm_group_$locale' and the frontend in 4.5 is able to read these. To preserve schema compatibility, I've updated the new UI so that it accepts values like 'civicrm_group_$locale'.
PR: https://github.com/civicrm/civicrm-core/pull/5049
So it turns out that 4.5 also saves records in civicrm_mailing_group with entity_table='civicrm_group_$locale' and the frontend in 4.5 is able to read these. To preserve schema compatibility, I've updated the new UI so that it accepts values like 'civicrm_group_$locale'.
PR: https://github.com/civicrm/civicrm-core/pull/5049