You declare the markets. The languages follow from that.
A passport is not translated once and then forgotten. You state which markets the product is placed on, and the page answers each visitor in the language of their market.


A market is a fact, a language is a consequence
Placing a product in a country is a commercial decision you have already taken. Which languages are needed follows from it, without you keeping a separate list.
Only one of the two follows the reader's language
The product address answers in the reader's language. The address of one published version is fixed, and stays in the language it was published in.
A visitor from a market you did not declare
They see the page, in one of the languages you declared. They are not shown a machine translation, because a translation you have not approved is not product data.
