I live in Belgium; in an area of Belgium that primarily speaks French. I happen to speak French as well (though I'm not originally from Belgium, I am French), but given the places I've lived in my life that's more a coincidence than anything else.
I do not speak flemish (be-nl). Yet, my page of the store is in flemish.
My browser (a Google browser!) is configured to ask for pages in english, and as a fallback, in french at a lower priority. There is a French version of the store, and it's still not sending it.
And a lot of people here in Belgium speak exclusively English. German is also an official language in the country, though only actively spoken in a small part of it. (Map: https://en.wikipedia.org/wiki/Languages_of_Belgium)
I have no obvious way of changing the language, other than a flag which rather points to changing the region. Turns out, in the region picker (https://store.google.com/regionpicker), "Belgium French" is a region, separate from "Flemish". When I click "Belgium French", a warning appears. In Flemish.
In other words, almost everything about language that store page can get wrong, it does get wrong.