the frame data is not correct on ex kunai actually. you have to time it just right and most knockdowns you can do into ex kunai will be tech rollable. a better approach to this hold the kunai and doing a jump kick or jump punch, that way if they tech roll you can let go of 1 and jump again into ex air spear for full combo if they didnt block the low and if they did you can get an almost unblock off that. the trick is if you use pad. with hitbox i can hold 1 and do a jump 2 and time it well but i cannot on pad. you also have to condition your opponent to just sit there and let you take this mix up most people jump when they see ex kunai so i like to do instant air tele let go of kunai and continue combo.
also i did not know that string came out if you did the full version, the f12 2+4 good shit.