This is as fitting a slow, sad and lamenting piece with alternating solo and chorale like sections. The 22 stop Długa Kościelna sample is perfect for this piece and only about 8 stops are used. In the score a Clarinet is suggested but here the Krumhorn is used.
Open this link for a paper by the Australian Harold Fabrikant which explores some of the reasons why Karg-Elert's music has been overlooked. http://www.ohta.org.au/doc/articles/fabrik3.html