FSC chain-of-custody codes are trackable online through their site. You gotta punch in that code to see if it's good for your supplier. Also, ask for the audit reports from the last two years, not just the cert. I learned the hard way to always get physical samples and match them to the spec sheets before ordering bulk.
Physical samples and spec sheets" is smart but so many people skip it. Why do you think that step gets dropped even on big jobs. Is it just time pressure or do suppliers make it hard to get real samples. Would you ever hire a third party just to check the wood before it ships.