If you want to Change the language, you have to use a Little bit c++. At least in Version 4.10 (my first Project).
https://docs.unrealengine.com/latest/INT/API/Runtime/Core/Internationalization/FInternationalization/index.html
With that i managed to make a blueprint library. From my menu i call then the node that i have created in c++. It is not that hard.