Complex sentence: On their return, they wrote a manuscript report on the disorganization and corruption in the government and smuggling, which was posthumously published under the title "Noticias Secretas de América" ("Secret News From America").
Split into simpler sentences: On their return, they reported on the disorganization and corruption in the government and smuggling. The report was posthumously published under the title "Noticias Secretas de América" ("Secret News From America").