Most high-quality CID fonts (especially CJK fonts) are proprietary.
: Open the PDF in Apple Preview (on Mac) or a browser like Microsoft Edge/Chrome , then select Print > Save as PDF . This often "re-flattens" the file and makes the text readable again.
When a PDF is created, it should include all the font data needed to display the text. If the software fails to "embed" the actual font, it assigns a generic identifier like .
When a PDF is created, if the original font is not fully embedded, the software creates a "CID" (Character ID) font as a substitute. Generic Naming: