Complex sentence: Notwithstanding Mikhail was a member of Soyuz Hudozhnikov, and he shown his paintings at official exhibitions, his art studio time to time were turned to site of gathering unadmitted artists to plan their next collective show or to discuss each other newly artworks.
Split into simpler sentences: Notwithstanding Mikhail was a member of the Soyuz Hudozhnikov, and exhibited his paintings at official exhibitions. His art studio from time to time was turned into a site of gathering for unadmitted artists to plan their next collective show or to discuss each other newly artworks.