No I don’t think you would get caught using Kodi on an Amazon Fire TV device. But because you COULD get caught and sued (now, AND in the future when technology advances, even slightly), why risk it when there are ways of obtaining the same content but taking Amazon 100% out of the picture (eliminating all risk of exposure)? As soon as you introduce the Fire TV stick (or any device registered to a company, whether that is Amazon, Apple, Samsung, or any other manufacturer), you increase your exposure to be sued. This is true, even if you are using a VPN on the router to which that device is connecting to access the pirated content (because the manufacturer still knows that device is registered to YOU).