Indigo Arts, Philadelphia’s longtime destination for folk art, is exhibiting a carefully curated show of works by five self-taught Cuban artists. Two standouts are Carlos Garcia Huergo’s painted and drawn works of cartoon characters on corrugated cardboard and Damian Valdes Dilla’s obsessive drawings of futuristic cities. Both artists have been hospitalized with episodes of paranoid schizophrenia, and their work reflects those acute mental states.