I'm writing a script in which I need to use a Spanish phrase historically used by a group of people to refer to themselves. The phrase is "Los Americanos Olvidados" or "The Forgotten Americans". The people who used the phrase were of Mexican-American descent.
The person who will be reading the script does not speak Spanish. Should I leave the phrase in its native Spanish, or only write the English translation? I'm certain the narrator could practice the phrase and have it not sound stilted, but nonetheless it won't sound natural. The rest of the script is in English.