I am trying to recover an old CoPay multi-signature wallet and want to find the keys that were on a device as a co-signer. I still have the physical iPhone, which has been upgraded and restored several times, as well as many backups of the iPhone. So far as I can tell, these keys were not stored in the backup, but perhaps I am mistaken.

If the keys are not stored on the backup, where were they kept on the device?