Why? Follow ups on Spin Knuckle hit are more than gracious enough for her to do her business.
Her CA doesn't really need what you're asking for here either. You just have to be aware of which button you using per where the character is. It hits just fine if you aware of that.
Sometimes if you strike an opponent at a distance other than point blank, the stagger of the opponent combined with the pushback means you have to very quickly change the confirm from the safer cr.MP to the riskier st.HP. And there's no real time to confirm this has happened until you're almost out of time to realize it's happened.
Keep in mind it doesn't happen that often.
Also the second thing is just a convenience thing to help in the heat of the moment. When it does whiff, it tends to graze the opponent's hairdo or toes, so adding a few pixels of comfort is fine. Unless you're against comfort.