Force your native app to reload? You can create a JavaScript action and put in the following code:
window.mx.reload();
Here’s a useful module for switching language on native. I ran into similar issues as you and was able to solve them by flipping a few extra switches. I don’t recall every detail but hopefully it works for you:
https://www.dropbox.com/s/3cmbj48ihu7c36f/NativeLanguageSelector.mpk?dl=0
Update : Resolved the issue by adding another Javascript action to remove the session before the mx.reload() javascript action in the flow as seen below.
JS_RemoveSessionNative :
Based on my experience, this refresh problem seem to only occur on the apk/ipa and not when viewing the app on Make It Native. This resolved my issue that I was having in Mendix 8.12.1. On a side note, after building a test apk app with Mendix 8.18.7 it seems to have resolved itself without the need for the Remove Session Javascript action.
Thanks Rob Funcken on the Mendix Native Mobile slack channel for providing the solution!