your problem is pretty basically.
you tried to make disemberment replays in the mod xspar.tbm, the problem there is, due to it meant being a sparring mod disemberments are disabled. so you cant, no matter how hard you try get a decap in said replays.
i changed a number in your replays to allow disemberments again. next time either change the game rules of the classic mod and do a replay there, or re check the game rules if you pick a mod to play in.
with those you should be able to make a decap with little to no effort since the moves looked pretty good, if you still have any issues, let me know.