It seems like putting the label for the dropdown hiding the other languages in English is not going to be maximally helpful for speakers of languages other than English. Customizing it with a translation in the user's browser accept language, or just using an icon (if a suitable one can be devised—a few ideas exist on Commons) would be more universal
Topic on Talk:Wikipedia.org Portal A/B testing
Thanks for the suggestion, Trey, I'll discuss with @MSyed_(WMF)!
A way to solve that would be making the OS/Browser prefered language always appear with the main languages around the globe, even if it has less than 1mi articles!
Yup, we did that exact thing in our A/B test and then pushed it to production. :)