If you do not need to edit the text and just need the document to look correct for printing or viewing: In a tool like Adobe Acrobat Pro menu to "Convert fonts to outlines".

Edit or create /usr/local/texlive/texmf-local/fonts/map/pdftex/updmap/cid.map (or system equivalent). Add lines like:

While they change per file, typical mappings found in community discussions include: Generic Name Likely Original Font Arial (Bold) or Times New Roman CIDFont+F2 Arial (Regular) CIDFont+F3-F6 Variations (Italic/Light) of the base font used in the doc

cannot be found, you aren't alone. This issue typically arises when a PDF was exported from software that failed to properly embed the original fonts.

Sometimes F1 might map to a Western font like Helvetica in a corrupt PDF. To discover exact substitution needs: