Interesting to read about the specs of that organ and the minimalism your recording was created with --- quite effective and well worked out!

Fun fact: This piece was known to me only because a friend of mine practiced it about nine months ago. When he did, he also asked me for a by-ear improvisation, which of course I couldn't deny...

His Hauptwerk practice video:
My Hauptwerk by-ear impro:

Hope you'll find these interesting enough to explore! :-)