If your grandma made you your favorite apple pie, would you tell her she didn’t actually make it herself? I mean, somebody else grew the wheat that was turned into flour, which was trucked on government roads to a store owned by somebody else. There are literally hundreds of people involved in the making of that pie.
Of course, there are also Aunt Betty’s apples that were used in the pie. You can’t have apple pie with apples, right? So Grandma didn’t REALLY make the pie, did she?
You wouldn’t ever really do that, would you? Your grandma sacrificed her time and energy to make you a special gift. Now, if it’s important to her to acknowledge the contributions of some significant others in the process, then that is her prerogative. I’m sure if Aunt Betty’s apples made a significant contribution to the process, she’ll be more than happy to acknowledge that. Maybe she’ll even make special mention of her own grandma that taught her how to bake pies, or perhaps that special home-ec teacher that made an impact on her. But that’s her place to do, not yours to point out.
You should never criticize grandma’s cooking. It would be rather rude. ESPECIALLY if you’re an outsider to the whole process.