Legal blindness isn't the same as total blindness. As wikipedia helpfully explains, "a legally blind individual would have to stand 20 feet from an object to see it—with corrective lenses—with the same degree of clarity as a normally sighted person could from 200 feet." Synesthesia is like crossed wires between the senses, where people with it can hear tastes or see sounds. A lot of the time it manifests as super strong associations between letters and colors, but tasting colors is possible, too