I think Belle Boyd is just chrome. I can't see what good she provides CSA, unless I just don't know how to use her. Her tool tip say that she provides a bonus to detection when commanding a stack. I aint havin no girl command a confederate division.
She has the master spy trait, meaning she gives you a +1 overall detect bonus in the whole theater she is in, but will disapears the next turn (has been captured historically IIRC).
Hofstadter's Law: "It always takes longer than you expect, even when you take into account Hofstadter's law."