Complex sentence: When it was almost finished, however, Gonzaga agreed to adding voices recorded on Vitaphone, a change prompted by the advent of sound films and their rise in popularity in the Brazilian market during the production of the film.
Split into simpler sentences: When it was almost finished, however, Gonzaga agreed into adding voices recorded on Vitaphone. This change was done because of the advent of non-silent films and its popularity in the Brazilian market during the production of the film.