The problem is that “Vidalia onion” has just became a generic name to describe a sweet onion, just as “bratwurst” has become a generic name to describe a particular type of sausage. So you can’t really go and retroactively reclaim the name.
Wisconsin cheeses is pretty general; for example, a Wisconsin cheddar or a Wisconsin blue means that they’re from Wisconsin, but the cheddar or blue describes the type of cheese. Maybe the Europeans should just go for inserting the word “true” or even their country name before the regional name that has now become a generic description: “True Brie,” or “French Brie,” for example, instead of trying to get the rest of the world to retro-adapt to their demands.
And Vidalia onions from Vidalia could be called something like “Georgia Vidalias.”
What the heck are you talking about 'retroactively'. The Vidalia onion industry started there in the 1930s and grew in popularity every year since then. It was only until the 1970s when they started seeing imitations and the "-like" onions grown elsewhere and created associations and the like to centralize the growing region. Besides being protected within the State of Georgia (1986) it is also a trademarked product, which IS offered at least some protection outside the state. In the end, I don't really care about the protections per se. I know when I buy a Vidalia onion, I always look to see where it was grown, so it's a moot point IMO.
To differentiate them from the Mexican Vidalias, they should be called Vidalia Vidalias. Then when the Mexican Vidalias become Mexican Vidalia Vidalias, the Vidalia Vidalias should become Vidalia Vidalia Vidalias.
Glad I could help here.