Aphantasiacs seem to be able to describe visual qualia as adequately as anyone else when the visual stimuli are currently present. But we do see descriptions differ between aphantasia and baseline in two cases: when the visual stimuli is recalled from memory, and when the visual stimuli is imagined. If it was about the difficulty of describing qualia, I don’t think we would see a difference between “visual stimuli present” and “visual stimuli recalled or imagined”.