My issue is that we are pairing nationality with skin color or ethnicity here. Those are not mutually exclusive. There are 2nd or 3rd generation Asians immigrants in Mexico, just as there are Mexicans living in Ireland, and Irish people in India, etc.. Somebody could be a fully integrated national but not part if the nations major ethnicity. Even saying AFRICAN-American is kind of pointless, like it matters where your grand-grand-grand-grand-parents came from. They're as much American as anybody else. We don't call everybody else European-American for comparison.
In movies meant to be historically accurate though it would be very weird to switch things up. Especially when so much was based on appearance at certain times.
Somewhat relevant to your second point, I don't like it when they speak English and it doesn't make sense.
Breaking Bad bothered me so much with how often the native Spanish speakers were talking in English, while in Mexico, with other native Spanish speakers. It isn't like they didn't allow Spanish in the show, there was a fair amount, they just arbitrarily decided that the scenes where it made the most sense to speak Spanish that English was the right language.
Well, that started out as a euphemism for "black" because some people decided that made them uncomfortable... Of course in the literal sense, Elon Musk is African American, even though everyone knows that's not what's intended...