'Macunaima," a spectacular epic comedy from Brazil, is the most exciting theatrical event yet seen at the Kennedy Center Terrace Theater.

At its final performance Wednesday, the headset system providing an English translation failed. Those in the audience who didn't speak Portuguese or Guarani, an Indian language, were faced with the possibility of four hours of incomprehension, armed only with a detailed written synopsis that had been provided with the programs.

It didn't matter. There were a few punchlines that provoked laughter only from the linguistically knowledgeable, but generally the sights and sounds of "Macunaima" were readily understood.

They were also uncommonly inventive and vivid. Director Antunes Filho and his Grupo de Arte Pau-Brasil appear to possess boundless imagination and energy. The epic form requires unflaggingly sturdy and inspired artists in order to sustain an immense vision over a long period of time, and this troupe fills the bill.

"Macunaima" was adapted by Jacques Thierot and the Grupo from a folkloric novel by Mario de Andrade about the life, two deaths and several transfigurations of a Tapanhumas Indian. The fellow romps with gods and mortals of both sexes, gradually growing from innocent infancy in the bush to mature sin in the big city, Victorian style.At the end of the show he leaves earth behind and becomes the Big Dipper.

Carlos Augusto Carvalho was a sensation in the title role, which required him to master every trick of the actor's trade. The ensemble around him moved, spoke and sang with absolute precision. The stage was nearly bare, but props served many purposes and the costumes were richly evocative. Particularly haunting were the scenes at a rich man's house in decadent Sao Paulo, where actors - powdered white - posed as nude statutes and Viennese waltz music played on and on.

The excitement level in the Terrace Theater dropped dramatically last night, when Theatre d'Aujourd'hui of Montreal presented "The Ups and Downs in the Life of a Diva: Sarah Menard by Herselves," by Jean-Claude Germain.

This monologue about a diva's vanities and sorrows seemed immobilized, as monologues on stage frequently are, and the English translation was delivered over the headsets in a somnolently dull monotone.

There were plenty of empty seats in the Terrace, but across the hall in Musical Theater Lab was overflowing for the Teatro de los Buenos Ayres production of "Stories to Be Told" by Osvaldo Dragun. A brief sampling of "Stories" revealed a "story theater" troupe of impressive versatility.

All three groups are here for the "Theatre in the Americas" festival. The Kennedy Center should import some equally ambitious experimental groups from its own country.