I have been using
let libraryURL = fileManager.urls(for: .libraryDirectory, in: .userDomainMask)[0]
let voiceMemosURL = libraryURL.appendingPathComponent("Group Containers/group.com.apple.VoiceMemos.shared/Recordings")
to get to the Recordings folder for Voice Memos. I'll read that post of yours over pizza here in a bit.
Thanks!