There is no official language in the USA. We speak English, Spanish, French, Arabic, Chinese, Japanese, Russian, German, Portuguese, Greek, Italian, Gaelic, and every other language known to man. Yes, English is dominant, but not to the exclusion of all others.
As for the names; they do not change because they are being pronounced by someone in their non-native tongue. The person might not say it correctly, or be able to say it or used to saying it correctly; but it doesn't make it correct. For example, regarding the name Sergei, "SIR-gei" is not correct. "SAYER-***" is correct. Generally, anyway. There are always exceptions. Andrea is a common name in the USA which has multiple pronunciations with the same spelling. Or the name Mikael; "MICK-ull" or "Mick-A-ull" with the same spelling.
Go tell Dustin Byfuglien that his name is not pronounced "BUFF-lin", but instead is pronounced "By-FUG-ly-enn" because "We are in America. And in America, we speak English. Period." See what he says to that.
WRONG AGAIN. English is our national language here in America. Official or Unofficial makes no difference. We speak English. Therefore, the announcers pronounce the names on the back of the sweaters in English. And yes, Frenchies get a pass because they started the fricking sport. So Richard is Rih-shard and Messier is Mess-ee-ay. But that's as far as it goes.