@ itworkedinthelab : If at all the Mailbox database which is holding the Primary hierarchy mailbox needs to be recovered, then you will have to restore the entire database directly in the production database path as we are recovering the hierarchy of the Public folders! Restoring it to Recovery database will not get the hierarchy back as hierarchy CANNOT be merged to production database if it is mounted with new fresh database files.
As you are recovering the database, any folder content which was modified, deleted or created after the backup of that database was taken might be lost. Once the database is restored and mounted the first thing that happens is that the primary hierarchy mailbox will initiate full hierarchy sync with all the secondary hierarchy mailboxes and only the hierarchy present from that last restored backup will be available
I hope the above answers your question!