I'd be willing to take your money.
There's a list of "legal" additives beer companies can use in their beer and not list on their labels.
If flavor aids are added through artificial or natural means, it HAS to be on the label. They don't have to list their recipe, but they do have to inform the consumer of whats in their beverage. Labeling laws are convoluted, but all consumable products have to follow the same laws. Even consumable products manufactured over seas and sold to the US have to follow our labeling laws (this does goes for more than just consumable products).
Go look at all the labels of beers 100% proven to use flavor aids. Like I said, rouge hazelnut brown nectar or shocktop apple wheat. Look up wild blue blueberry lager. All the labels state the use of natural or artificial flavors.
Its flavors made from a laboratory, such as your pumpkin pie, graham cracker or butter nut extracts that has to be on the label.
If I were to make almond extract from a peach pitch, then it would have to be on the label as natural flavor
If I were to make almond extract from banana and vinegar (to get the same compound found in the peach pit) then it would have to be added to the label as artificial flavor.
Here's a link to the FDA
It says, "(c) a declaration of added flavor, such as any spices, natural flavors, or artificial flavors, as specified in 21 CFR 101.22(h);"
Decleration means announcement FYI
You're barking up the wrong tree trying to clone this beer. That's why it's been unsuccessful for several years.