I have never in my life seen “butter aroma” in butter (from US).
Here’s a few I could find from a quick search: https://www.albertsons.com/shop/product-details.960493010.ht...
https://www.albertsons.com/shop/product-details.960047103.ht...
https://www.albertsons.com/shop/product-details.138250183.ht...
This Reddit post says the natural “flavoring” is lactic acid to replace salt as the preservative, but obviously you can’t be sure with that labeling:
https://old.reddit.com/r/AskCulinary/comments/26q208/natural...
But I see the Kerrygold equivalent, which is also sold in US stores doesn’t have this.