@Janu sree I would really question if the benefits of having it on the megamenu bar is going to out weigh the level of customisation you're going to have to make to get this working.
To build the megamenu, the header widget calls the 'Employee Center Navigation' which is read-only, so this would need to be cloned. And cloning widgets means you need to check them with upgrades/patches, as they don't get flagged when the OOB widget is modified. You would also need to modify the server script on the header widget to point to the clone version of your 'Employee Center Navigation' widget. Once that is done, you can add the language picker widget to the clone version.
I was able to drop it under the div for <!-- topic-based navigation menu --> and was able to get it to display like this
