The three defects should first be recognized as distinct analytical questions; an unfamiliar word should not be assigned to one category without evidence.
DefectQuestion to ask
Tanafur al-hurufDoes the letter sequence make pronunciation burdensome?
GharabaIs its meaning or use unusually unfamiliar?
Mukhalafat al-qiyasDoes the form violate established linguistic analogy?
A rare word is not necessarily malformed, and a correctly patterned word is not automatically easy to pronounce. The categories must remain distinct.