Complex sentence: During the making of "Kashinath" (1943), Bose had a misunderstanding with B. N. Sircar and did not go back to New Theatres, with which he was associated since it was established in 1931.
Split into simpler sentences: During the making of "Kashinath" (1943), Bose had a misunderstanding with B N Sircar. After completion of the film, he did not go back to New Theatres, with which he was associated since it was established in 1931.