Complex sentence: His date of birth was long a subject of controversy among researchers; only two centuries later was the exact date established according to the documents: 29 of June, 1796, leading to the involuntary error on the inscription.
Split into simpler sentences: His date of birth was long a subject of controversy among researchers. Only two centuries later was the exact date established according to documentary evidence-29 June 1796, leading to the involuntary error on the inscription.