In the main part, I want to speak about the new Android 13 feature "Per-app language preferences" which was introduced for all Android versions in AppCompat-1.6.0 this January.

I will explain how it works under the hood and what is wrong with how it was backported to Android 12 via AppCompat Library. I will show how AppCompat Library replaces resources, recreates the whole activity stack, syncs locales, etc.

Indeed, the experience is not the same for all Android versions, which we should keep in mind. I am eager to share my experience and suggest my solution for discussion and how I was able to unify it.

To spice it up, I have my story of ups and downs, which is quite entertaining and, at the same time, useful for the audience; how I broke the app for Indonesian users because of locales.