The problem is normally when you have to change languages and, as me, you have daily conversation in two three different languages.
The keyboard is easily configurable adding new languages through the settings interface and dragging over the bar of the virtual keyboard.
The voice recognition will work consequently to fit the current keyboard.
It's not the same case in the Voice Control of the Google Search widget where you can only use the current language you've selected from the settings. It would be nice to have a drag/slide feature to switch between voice recognition. Ex: If the name of the person you are calling is Spanish and you don't know how to pronounce it in English you should be able to slide from English Voice Actions to Spanish Voice Actions recognition.
One of the problem to face is that the Voice Commands are not translated into the different languages or not triggering the Action.
-> In English "Call David" is triggering the Voice Call to my friend David.
-> In Spanish "Llamar a David" is just offering a text search for that sentence.
-> In Italian "Chiama David" is barely recognized and "Call David" is not making it better.