Ah, I see you answered my question already!
The thing is, this is not about trust or bad faith but about liability (sorry I
am a lawyer

). Our trust level is, should be, dependent on expertise. But the fact is, at ANY level of expertise mistakes are possible.
Take Christie’s, which is the golden standard. They need to use authenticators and they use the best (as indeed Bababebi) to protect their reputation. Yet they have made mistakes including some famous blunders. Authetication is a very muddly thing. That’s why authenticators in practice what they usually give is an informed opinion, and have no liability. It is the seller, like Christie’s, bearing liability if the item is deemed fake. With fine art it is difficult to determine who’s the authority for this if the artist is no longer alive or their state active, and there are some fascinating lawsuits out there. With Hermes, it is simple, as the still active manufacturer company they “own” the intelectual property of their products. If Hermes won’t accept a bag to all effects the bag is a fake and the seller is liable. Who has made a mistake is, from this perspective, beyond the point because at the end of the day anyone can make a mistake and you and me, as lay people, cannot have certainty one way or the other. Ultimately, when you buy a Hermes bag you buy the privilege of a bag that will be served by Hermes forever, and that is a part of its value. So I think you should not have any problem to recover your money if worst comes to worst, which I sincerely hope it doesn’t.