Plenty of examples of this. According to IMDB, the actor who played the village headman in Indiana Jones and the Temple of Doom could not speak a word of English: he recited all his lines by rote. And with a credible - if a bit stereotyped - accent!Cyril Haearn wrote:But trained actors can fool us, I read about one who delivered a perfect speech in Danish although he could not speak the language at all
Probably there are lots of opera singers out there who don't speak the language they are supposed to sing in - although they can sing their lines perfectly.
Speaking for myself: well I can recite a few lines of, say, Goethe from memory - although I don't speak German. I doubt if my accent would pass muster, though! Probably there are people on here who can surpass that...