Original sentence: In these cases, accessibility tags and re-flowing are unavailable, and must be created either manually or with OCR techniques.Moreover, tagged PDFs can be re-flowed and magnified for readers with visual impairments.Problems remain with adding tags to older PDFs and those that are generated from scanned documents.These processes are inaccessible to some disabled people
Edited sentence: Moreover, tagged PDFs can be re-flowed and magnified for readers with visual impairments, however, problems remain: the difficulty in adding tags to existing, or legacy, PDFs, e.These processes often are inaccessible to some disabled people, nonetheless, well-made PDFs are a valid choice as long-term accessible documents.for PDFs that are generated from scanned documents, accessibility tags and re-flowing are unavailable, and must be created either manually or with OCR techniques