(Though not an Android app, the worst offender is Adobe Creative Suite. I have a workstation set to Japanese just so that Illustrator and Acrobat will run.)
Some apps that misbehave without ja-JP
The new Google Maps app and Google Now are two in particular that eventually drove me to change my phone's language and locale to Japanese. Even if Google allowed separating these two fundamentally different concepts, there would still be issues with these apps. Also, Sony's Xperia contact app will organize all non-English contacts under a single symbol icon.
I have confirmed with folks at Google that not all Now features are available, such as disaster alerts, unless language and locale are set to Japanese. I've also had some generally wonky behavior with Google Now when my system is set to en-US.
With Maps, if I search for a station name in Japanese, such as 東京駅, the station is found just fine, but then all the information gets displayed in English, and when you check your search history, there is not record of searching for 東京駅 but for "Tokyo Station," and to make matters worse, this is sometimes displayed in 2-byte font romaji (which is not English), breaking expected functionality.
The text "Tokyo" and "ＴＯＫＹＯ" are not the same thing!
App Settings Xposed module to the rescue
The Xposed framework is just awesome. It allows you to tinker with individual apps and system files without have to actually tinker with them. For example, old the b-mobile signal bars fix required decompiling, patching, then recompiling. The new fix just uses an Xposed module.
With the App Settings module, you can change all sorts of app behavior, including screen resolution, orientation, and fullscreen settings, as well as many other options, including revoking individual permissions. You can make an app resident in memory, so you won't ever complain when a hangout request causes your candy crush game to close and you lose your progress. Version 2.2 of the Xposed framework now includes a repository of modules that you can download from within the app.
- Android 4.03 - 4.3
- Xposed Installer (v 2.2 or higher; apk)
- Download and install the most recent version of the Xposed installer.
- Launch the Xposed installer, tap "Framework" and tap "Install/Update".
- Reboot the phone.
- Launch the Xposed installer, tap Download, and the refresh icon 🔃, then search for or scroll down to App Settings.
- Select it and tap download and install.
- From the Xposed installer main menu, enable App Settings by tapping the check box, then tap the module and chose the app to modify from the menu.