I mentioned CommVault just for an example purpose, they have a unique propritier feature (paid option) wherein it enables you to restore the NAS data to Non-NAS devices such as standard OS such as Windows/Unix standard machine.
I guess in your case it does not apply, b'cos the backups were most probably taken by another Backup software ( I dont know which). Every backup software has a proprierty information when writing to tapes and it will not allow other Backup software to read those tapes.
Coming to your scenario, 3-way backup: In this backup types, even though the backups are read/written by Media Server but you can only restore the data to NAS location (In 2-way, NDMP Head reads and writes the tape) .
In 3-way : It will ask you for restore location path which will be similar to the original location that was backed up. However, you can give another locaion but on the same or another filer. My question is : Are you able to catalog the tapes ? Are you able to browse and go to restore directories ? Once you select the data to restore, you need to enter the path to NAS location. Hence, you will need a NAS path for the restore.
Is it possible via Simulator ?
Well, theoritically yes; but first step would be to get the simulator up and running and then add this NetApp Simualator NAS using Port NDMP 10000 to the backup software. Once it is detected, it should show up as NAS destination for restore selection purpose. Once you trigger restore from the backup software, Media Server will load the tape and start to read in order to restore, once it has reached the correct offset for the director/file to restore, it will begin to restore. Now, it is only to be seen whether restore to the simulated virtual disks reported as NetApp volumes is possible or not ? If the tapes were NDMP dumped volume level, then entire dataset will be restored, and depedning upon the size of the volume I doubt simulator will be able to take it. Once again, I have only done restore in my lab from Backup-2-disk Medias, and not physical tapes, so I can't really comment if it will work.