Thank you for actually reading the code - that's more scrutiny than most of this thread, and your read is accurate.

On the cookie listener: cookies.onChanged is scoped to an add-on's host permissions, so it only receives changes for keepa.com and the Amazon domains - not the whole browser. The first two lines of the listener discard anything that isn't keepa.com/extension. It exists because the chart is embedded from keepa.com, and Total Cookie Protection stops that frame from reading its own cookies, so the add-on mirrors them across.

On understating: fair, and we've changed it since. Two of the three labels were wrong - "website content" (we transmit none) and "personally identifying information", which was only ever the Keepa account token and is now "authentication information". The listing now spells out what each remaining category covers. If a specific line still reads as understated, tell us and we'll fix the wording.

On the rating: we understand the logic. The cost is that the star is what the ranking and most visitors register, while "no new harmful code has been added" is the part they don't read. We'd rather that sentence were the findable one.