I’m saying you should NOT use the Input Transformer at all to accomplish your task. What you should use is a Drum Map.
The Input Transformer, the Logical Editor and the Project Logical Editor all basically work in the same manner although they are designed for different tasks. And they are tricky to understand, especially at first. But once you know how one of them works the others will make sense. I think the easiest one to learn with is the Logical Editor (the LE not the PLE). If you want to learn the Input Transformer I’d advise learning the LE first.