Regarding the first part of your question, the logical thing to do is call both the company selling the product and/or the hashgacha and ask them who is the author of that statement. In reference to part b of the question, that’s something you have to take up with the author of the statement.
Regarding ou and grape products, they specifically discuss this on their website ou.org and the short answer is, if it has an ou then all halachos involved not just “kashrus of the ingredients” are taken into consideration. You may ultimately disagree with their psak, but that’s a different discussion (akin to your shayla regarding the pita and kvias seudah).
Does the neemanus of someone take a hit because you disagree in a halacha regarding kvias seudah? Not saying you shouldn’t look into the shittos of the hechsher, perhaps they pasken in areas of kashrus of ingredients or bishul etc differently then you would at home. Verifying standards shouldn’t be triggered by statements regarding a bracha though, imho that is caveat emptor number 1 when it comes to a hechsher.