No, what I said is true if you use zero-based numbering. But when communicating with others in English, the label “first” refers to the element with the smallest index. In zero-based numbering, the label “zeroth” refers to the element with the lowest index. It’s just not the default in English, but you can definitely use zero-based numbering in English if you’re willing to edit the configuration files.
Maybe someone can correct me if I’m wrong, but doesn’t Wayland’s security model intentionally prevent this type of “tampering” with another application’s display?