I stand corrected.
I just tested it out and it doesn't work on Mamiya's low arrow. It reflects Juda's 236C though.
What terrybogard said about the sjc. A's timing is true, but because you say you can get at least 2 hits it sounds to me like the opponent is too low when you hit them with the 2nd standing D xx 236D. Either close or far D will work but I think you'll want to time it so that close D comes out because it hits above Ken, the opponent is closer to you, etc.. Ideally you want them above Ken's head when you smack 'em with close D but the timing is pretty lenient.
If you're using the 236D > j.C, j.D set up, then you must j.C on the way up, pause, and j.D as Ken falls. It's kind of like doing the up+HP in Iron Man's infinite because you want Ken to be closer to the ground while keeping your opponent floating above you.