Swift is not exempt from the 1/256 uncertainty. This was well documented several times over at azure.Due to this, there is always an extra 1/256 chance that any "100% accuracy" attack will miss, and that any high CH rate attack will miss (+~0.4%). The only exception is Swift, which does not perform this check, and thus cannot possibly miss.
Jump kick will cause 1/8th recoil on a miss. Only Hi Jump Kick does 1 HP recoil on a miss.Hi Jump Kick and Jump Kick
If it misses, rather than having a recoil damage of 1/8 of what it would have dealt, it only makes you lose 1 HP.
Just a slight nitpick on semantics... since the attack works on Stadium, it isn't fair to say you shouldn't use it "under any circumstance".Focus Energy
Not only will it not make your Critical Hit Ratio higher it will quarter it instead. Do not use under any circumstance.