The three defects address distinct questions.
DefectDiagnostic question
Tanāfur al-ḤurūfIs articulation harsh?
GharābahIs the intended meaning unduly obscure?
Mukhālafat al-QiyāsDoes the form follow accepted morphology?
A careful analysis tests sound, intelligibility, and morphology independently. A sound individual word must be free from all three listed defects.