If I get a message in German then I can either decide to translate it or ignore it. As you said, it's not possible for the cic to know the language of everyone, especially in a vast alliance of 50 players from many different areas. The easiest, simplest, most efficient way is to send the message in the language of the alliance as decided by the cic. If a player chooses to repeatedly ignore it then they must face the consequences, or the can act upon it if required, firstly by reading it via a translator then understanding and acting on it.
EA have enough trouble getting things right as it is, why add something as complex as translation to the game when it's not needed. A script to add a code beside a players name (standard international country codes would do although some are bi or tri or even more lingual) to help, maybe. I wouldn't be adding it in, it's unneeded in my opinion.