douglasselph

The following allows you to very easily flip between languages and country on Android.

This will IMMEDIATELY cause the change without even needing to shut down the target testing app.
(That is, the currently displayed page will reloaded.)

You first need to install this APP on the phone:
https://play.google.com/store/apps/details?id=net.sanapeli.adbchangelanguage&hl=en

Then to flip copy and paste one of the lines below in a terminal.