If I recall properly, it's because they all use translators. There was something about it in the whatever it's called log you have.

The Omnitool does live translating. In the first one when you encounter the broken prothean VI. He seems to speak English but, I had Garrus in my party, a party member will mention how he cannot understand it, but Shep can because the Beacon.

Cipher, not beacon.

You made a post to correct something I said almost 9 months earlier?