‘My Mexican Shivah” is a surprisingly universal story, even if its title implies otherwise. John Sayles serves as an executive producer, but the film is unlike his Spanish-language “Men With Guns” or any mainstream Latin-American films in recent memory. In fact, it’s somewhat difficult to place — unmistakably about the Jewish Diaspora but also conjuring elements from the particular brand of familial hysteria found in so many Latin-American comedies. Director Alejandro Springall’s sophomore feature provides loads of insight on its ensemble of characters, who are not exactly pleasant company but are unmistakably human.