something for you, perhaps I am close: reading locale configuration:
https://android.googlesource.com/platform/packages/apps/Launcher/+/master/src/com/android/launcher/Launcher.java
this shows that only locale is written into config (launcher.preferences), not LocaleData – they are taken from the database
https://android.googlesource.com/platform/packages/apps/Launcher/+/master/src/com/android/launcher/Launcher.java
this shows that only locale is written into config (launcher.preferences), not LocaleData – they are taken from the database