Complex sentence: He wrote a number of chess books in several languages and has contributed regularly to the "Chess Informant" semi-annually (more recently, thrice-yearly) compilation of the world's most important chess games.
Split into simpler sentences: He wrote a number of chess books in several languages. He also contributed regularly to the "Chess Informant" semi-annual (more recently, thrice-yearly) compilation of the world's most important chess games.