Can I get the used Keyboard language from Android device?

In case you were interested and it still mattered to you, I started making a native extension that could do what you would like. The ANE can also pretty much do everything the Locale class in Java can do. Im still wrapping things up and adding onto what the Locale class in Java does. Will post back with a link whenever I get to a good "finished" state for others to test and use.

Locale | Android Developers

If I understand you correctly and are just wanting to get a string value of the language name or country, then in theory yes. According to the link below, you should be able to get the current language but you will need to create a native extension to do so. The first answer has no votes, but it seems like an easy way to do it.

java - Get keyboard language or detect user input language in Android - Stack Overflow