I'll put my name on this list too - I've noticed the same thing, with quinoa nonetheless. I never seem to digest the outer hull of quinoa, so it is a good indicator of bowel transit time.
Maybe this points to a weak ileocecal valve? I'm concerned as well, specifically because if we are bringing undigested food from the small intestine into the colon, then some of it may be staying there when we finish the enema process and make things worse. I guess it would be wise to keep doing enemas until everything is definitely out.