Expert means nothing. Provenance is not a story given by people who seem "nice". Being an antique's appraiser is something you can claim without credentials. It's even worse than getting a diploma from a diploma mill from an ad on a pack of matches. You can become a certified appraiser by essentially paying membership dues to some unregulated outfit. The training is a guide to where to go to look up realized values. My now deceased father had such a license. It was useful to have for his auction business to present to lawyers as evidence of competency .
As an anecdotal example, I remember him being asked to sell a piece of furniture for an estate where the family produced pages upon pages of "evidence" that the chest was a colonial piece from the late 1700s (most of it was genealogical work). Words to the effect that some dealers had offered them "big money" for the piece were also given. Upon rudimentary examination, it was noticed that the entire carcass had been poorly made up of fruit boxes from the early 20th century. Excuse me for saying it, but some people are nuts and dangerous. My father ended up selling that piece with their paperwork with a caveat, but someone saw fit to not bother looking for themselves. If the expert is not you then be VERY careful. The horseshit attributions we have seen on the COOI are testament to how wild some people's ideas can be.