The relaunch combo is kinda tricky to land on small characters, who were you trying it on?
Also, you seem to be missing a 5c after 214d~c, I assume you're doing it (stuff 3c 214d~c (slight pause) 5c j.cx5 land 2c 4d~d j.cx5 j.cx5 j.214b). Try doing 5c 2c after landing and before 4d, it might help depending on the character.
Anyway, not much can be said about the timing if you don't say who you're playing against.