yea 6C CH , sorry..
and triple dash is the way you tapping your joystick 3 times so you get more momentum..., instead of the normal 2 times for dash cancel
you can see the example of that in stunedge combo videos
no the 4.5k 6C is not corner at all..
I usually try to do the 4.3k instead since the 4.5 is a bit harder lol..
so it'll be anywhere on the screen with
6C(CH)>triple dash > 6C > 2D > 6B> sekkajin> 6C > 5C > jC/j2C > jump cancel > j2C > 214C.
I usually just do j2C> 214C right away for 4.3k but I get better oki.
if you are anywhere near the corner you can start the corner loop substituting the 2D with 6D for more damage..., also you can go for 623D or 214D
if you want the real damage 6C provides the best damage jin combo, 4.5 k meterless from 6C and up to 6-7k with 100% meter
PS: I mean if you have time to do 2C most likely you have time to do 6C too like, off whiffed DP or whatnot