Case 1 — المستشزر: Heaviness of articulation points to sound discord.
Case 2 — موددة: A failure to use expected assimilation illustrates violation of morphological analogy.
Case 3 — افرنقع: The sense “withdraw” is expressed by a rare form; the issue is obscurity.
Case 4 — اجتمع: A familiar expression meaning “gathered”; a sequence of several letters alone does not establish a defect.
A good analysis first identifies the form and meaning, then names the precise technical cause of any deficiency.