But the lingua franca in Europe has changed several times the last 1000 years. First it was Latin, then it was German for most of Europe until French took over somewhere 15-1600 and today it is English. Besides we can't even be certain they speak English on Beta - considering they were multicultural from America they could just as well speak Spanish, or more likely a new language with characteristics from both languages.
Miles spent a year or so on Beta as a teen. I'd expect him to have learnt the most common galactic lingua franca then if not earlier. That he doesn't speak every language doesn't mean Cordelia neglected that part of his upbringing.
Now I am not saying the new intergalactic lingua franca is NOT descended from English, I am just saying that the whole thing is likely a lot more complex than that.
Re: Excerpt on languages (non-spoilerly)
Miles spent a year or so on Beta as a teen. I'd expect him to have learnt the most common galactic lingua franca then if not earlier. That he doesn't speak every language doesn't mean Cordelia neglected that part of his upbringing.
Now I am not saying the new intergalactic lingua franca is NOT descended from English, I am just saying that the whole thing is likely a lot more complex than that.