We don't really deal in guarantees in medicine. Also I don't know if your symptoms are due to your sleep apnea. If they are then good recovery would be anticipated.
Is a full neuro-cognitive recovery guaranteed with full compliance with CPAP treatment? I am still finding it hard to focus and think and I've been dead tired today... I was in bed for more than 8 hours... The CPAP is working as intended because my AHIs have only been at around 1.2 on average since I got started on it.