Result: The F1–F7 fonts will now render using local substitutes without any risky download.
To fix your issue safely:
Engineering software often exports text as generic F-series fonts when the original SHX or TrueType fonts aren't properly converted. How to Resolve Missing CID Font Errors cid font f1 f2 f3 f4 f5 f6 f7 fonts free verified download
The "F1, F2" labels are just internal shorthand for the first, second, or third font used in that specific document. Why You Can't "Download" These Fonts Result: The F1–F7 fonts will now render using
Many CJK CID fonts, such as Noto Sans or Source Han Sans, are hosted directly on GitHub by their developers. Why You Can't "Download" These Fonts Many CJK
The terms are typically not actual font names you can download; they are placeholder names created by software (like Adobe Acrobat or InDesign) when a font is not properly embedded in a PDF.