* changed "Muestra las letras romanizadas en japonés, coreano y chino." to “Muestra letras romanizadas para japonés, coreano y chino.” ("para" fits better when listing languages here.)
* changed "Fondo" to "fondo" (unnecessary capitalization.)
* changed "Puede" to "Puedes" ("puede" is formal when the rest of the document uses informal "tú" (e.g., "si activas", "verás").
* changed "Descargar lista de reproducción local" to "Descargar una lista de reproducción local" (grammatically fine, but this is much more natural Spanish)
* replaced "No hay instancia de pista" with "No hay pista en reproducción" (this sounds like a direct translation from google translate, the new phrase is now native spanish sounding.)
* replaced "Deja la música sonar..." with "Deja que la música suene..." (again, this sounds like it was translated directly from English, this is the correct phrase.)
João Silva