I dont think its possible in the game anymore. In pre-cu era, you could only make master in your profession if you have tought one or two of your skills to a new player. You could do it by using the radial menu on the player. In the radial menu it was an option to "teach", and with this option you could not only teach skills but languages as well. Since this option is remowed from the game i dont think its still possible to teach languages.