Voice Memos visible on iTunes, but files appear to have been deleted on iPhone. Can I recover?
so sorry that this happened to you. Indeed, iTunes is probably listing the voice memos from the plist file - if you haven’t found the recordings themselves with iFunBox (.m4a files), they are probably lost unfortunately. You can have a look again in Media/Recordings and hunt for these if you haven’t already.

Sorry I can’t help more.