The article talks about Microsoft, and boy, it's even more terrible in some respects: for example, language of some Office tools like Excel is bound to the organization ! I worked for a French company, and I was forced to use web Excel in French, including keyboard shortcuts being FR-specific ("ctrl-g" for "bold" - "grossir"). I had my language set to English everywhere in browser, OS, MS profile, Office profile etc.…
Swiss German here. Je suis bilingue. My OS is set to English with a Swiss German keyboard layout. This works fine everywhere. Except: The Microsoft Store app just keeps on running in French with English content. No German to be found. It looks damn silly.
// Edit:
Okay so the issue can be resolved as follows (Windows 10): Windows Settings -> Time & Language -> Language -> Preferred Languages -> Order it so that "English (United States)" is at the top
I previsouly had "English (Switzerland)" at the top. This order influences the "Apps & websites" setting at the top there.
With "English (Switzerland)" my section headings in the Store were French, e.g. "Films et TV" but with "English (United States)" at the top I get "Movies & TV". Of course the section headings, callouts, etc. otherwise are still a mixture of your MS Store region (German in my case) and the Windows display language (English in my case).
Why "English (Switzerland)" would result in French... I don't know.