They didn't make a such changes to Cait.
What they did was just changing her passive counter from an on-hit effect to an on-attack effect.
They didn't have to make exceptions for Shiv, since nothing about her headshot changed. Just the counter is counting differently now, instead of counting the targets hit, it counts the attacks casted.
Kleptomancy is a different case. It is coded as a spellblade effect, just like the effects of

They all are spellblade effects when it comes to code, you would have to change Kleptomancy's code, not the ability.
And if you want to make the exception: That is inconsistent as hell. You want them to be unable to proc Kleptomancy with it, because it states that a spell is enhancing your next AA with the effect..... Which is worded exactly the same way like the spellblade effects.
It makes no sense for these spells to be able to trigger sheen, but not Kleptomancy. The effects are phrased exactly the same. So why should it work with one of them and not the other?
This is inconsistent, something that Riot clearly tries to avoid as much as possible.