I just went in the lab and tested this last night, if you do: 5a, 5a, j.c, 236c+d facing your opponent when they are backed in the corner you will always cross them up and so you should input the 214a as if your back is to the corner. Just my experience, I don't think it's character specific but I tested it with akihiko as training dummy. I could see the jump cancel being helpful for people who have trouble delaying the 214a but i don't think that's hard once you get the timing.