The box would prove nothing.
HOW MUCH OF THIS IS BELIEVABLE
It is the majority view that someone inspired the Jesus legends but the questions being asked are legitimate. What is the basis for the assumption of historicity? Are these valid when analyzed? Bottom line, some kind of artifact supporting the historical Jesus who inspired the stories would be extremely timely and fortuitous given the currently hot debate. The same collector was paid $400,000 for the pomegranate. I'm sure he is looking for a buyer or this.
Carrier's book does a pretty nice job of summarizing the issues and evidence: