Help with a VERY SIMPLE macro

You don't really need Keyboard Maestro for this simple task.

First, why don't you just use an Excel formula:
D2: =B2
E2: =C2
and then copy down.

But if you really want a macro to copy, then it usually it is best to use Excel VBA when the entire workflow is within Excel.

Try this:

###Excel VBA Macro

Sub Set_Cell_Offsets()

    activeCell.Offset(0, 2) = activeCell
    activeCell.Offset(0, 3) = activeCell.Offset(0, 1)
    
End Sub