Complex sentence: Busnois remained in the employ of the Burgundian court until 1482, but nothing exact is known about his exploits between then and the year of his death, 1492, while working at the church of St. Sauveur in Bruges.
Split into simpler sentences: Busnois remained in the employ of the Burgundian court until 1482, but nothing exact is known about his exploits between then and the year of his death. At the time of his death, in 1492, he was employed by the church of St. Sauveur in Bruges.