Hi,
User Role Editor uses the same DB as WordPress itself does. More, URE does not create/use any custom DB table. URE stores all information at wp_options DB table (db prefix may vary).
Roles are updated in place – the same db record where WordPress stores its own internal roles. So if you lost user roles changes after restore DB from backup – it’s an earlier made backup, or backup made from other site or subsite of this multisite network.
