Seems worth mentioning that the four ways you list for events to be causally linked are the building blocks of d-separation, not the whole thing. E.g. “A causes X, X causes B” is a causal link, but not direct. And “A causes X, B causes X, X causes Y, and we’ve observed Y” is one as well. Or even: “A causes X, Y causes X, Y causes B, X causes Z, and we’ve observed Z”. (That’s the link between s and y in example 3 from your link.)
Seems worth mentioning that the four ways you list for events to be causally linked are the building blocks of d-separation, not the whole thing. E.g. “A causes X, X causes B” is a causal link, but not direct. And “A causes X, B causes X, X causes Y, and we’ve observed Y” is one as well. Or even: “A causes X, Y causes X, Y causes B, X causes Z, and we’ve observed Z”. (That’s the link between s and y in example 3 from your link.)