Overall it's a great add-on, there's (IMO!) only one functionality that it's lacking: ability to configure per-domain language settings.
According to github conversation about it - it won't be implemented. Unfortunately.

Great! Does what I want it to do. Adding new languages is quick and easy. Haven't found a better one yet, so I would highly recommend!

Excellent for when testing i18n while developing web apps. Totally recommended.

It works to force english in ansible tower.

perfect

very useful and easy to use. A must have for bilingual users!

Really great extension and useful

Nice, thanks!
Just one thing missing: remember the selected language for each site.

Thank you

Einfach und tut genau was es soll. Damit kann ich nun endlich die App-Beschreibungen auf Englisch im Google Play Store lesen und muss mich nicht mehr mit den unverständlichen automatischen Übersetzungen herumschlagen.