The Fed has no gold stock. Every ounce in the New York Fed gold vault is owned by someone else and is open for audit whenever the owner, be it Germany or France or the Netherlands or whoever, want to. I can't speak for Fort Knox.
Bundesbank didn’t review their gold with an external auditor. They weren’t allowed in that day.
But they were allowed in with an internal auditor. Doesn’t do much to help confidence that there is never an external auditor.