Yes you read it right. It is possible to run each app in separate language while keeping your android phone language as it is. In the market there is an app called "Localized Apps" using which one can achieve this. It creates shortcuts which allows user to specify which language and country code the application should use each time.
The only drawback of this thing is, it increase the launching time of the main app as it first applies localization to that app and than it starts the app. Of course this process will slowdown the launching only but its fine if we are really in need of some localized app.
Just think of using Google maps in Italian and while the default language of your Android device is set to English. For such type of customization Localized Apps is a quicker solution. On your home screen you will be allowed to place multiple shortcuts for different types of Apps, each set up with different language.
The application supports ISO639 languages such as English(en),French(fr),Spanish(sp) etc. and also for ISO3166 countries like United States(us),Britain(br),France(fr) etc.
When the application is loaded it displays with a Create Shortcut button along with the detailed description. If the user wants that the browser to be launched in French than the user must input ‘fr’ in the shortcut language field and ‘FR’ in the shortcut country field. Localized Apps from Android is available for free and anyone can download it from the Android Market.
Download Localized Apps from Android Market
or use this QR code