[Gameplay] Neeko 3rd hit/TF 4th hit don't trigger Arcane Comet, but Jax/Kennen do! - video proof

I don't know which of these is the bug, and which is the correct behavior. But they behave inconsistently, so one of them is a bug. Should the Xth-hit abilities apply spell effects (Arcane Comet/Manaflow Band) or not?