A 32-year-old male veteran with PTSD has been receiving prolonged exposure therapy for 10 sessions and was started on sertraline 150 mg daily eight weeks ago. His PTSD Checklist for DSM-5 (PCL-5) score has decreased from 58 at baseline to 41 at today's visit. He reports decreased frequency of intrusive memories and nightmares, improved ability to engage in previously avoided activities, and less hypervigilance in public settings. However, he continues to experience emotional numbing, difficulty feeling close to family members, and persistent sleep-onset insomnia. His wife reports he has been more engaged at home but still has angry outbursts approximately twice weekly. The PMHNP is evaluating the treatment response. Which interpretation of the PCL-5 score and clinical data is most accurate?