1) That's toy canon, it frequently differs from show canon (e.g. pink Celestia)
2) Since you used the example: Lots of people call the US "America" even though it's only part of it
3) Also as you're already talking about the US: There are over 300 languages spoken in the US (about half of which are native to it)
4) I will call it what I want to, and you're free to do the same
Seems "English" is more likely to become canon anyway, given that they've already mentioned "French" things.