Cummerbunds are actually waistbands that one can find in many varieties. The correct spelling is actually “Cummerbund” not “Cumberbund.  While Merriam-Webster Dictionary does list “Cumberbund” as an alternate spelling, this is pure because of how often it is misspelt and pronounced.  Such is the way that language develops.  But for now, and originally, “Cummerbund” is the correct spelling. It is not a tough pronunciation. The word sounds like kuh·muh·buhnd.