Complex sentence: One of his most acclaimed prodigies, Project Superstar female champion of the 1st season, Kelly Poon, whom he had painstakingly trained her for 3 years before she achieved stardom through this nation-wide Chinese singing competition.
Split into simpler sentences: One of his most acclaimed disciples, is Project Superstar female champion of the 1st season, Kelly Poon. He had painstakingly trained her for 3 years before she achieved stardom through this nation-wide Chinese singing competition.