Really? Can you even copyright a font? As far as I know, fonts can't be copyrighted, meaning they can be used by anyone without needing a licence. IANAL, but it seems like font users aren't required to comply with attribution and share-alike requirements of the CC licence.
With vector fonts containing copyrightable code, are you referring to e.g. TrueType hinting, or OpenType shaping (or very avant-gardely, WASM shaping)? I should hope the glyph-drawing instructions don't fall under this definition of code, because that'd maybe mean SVG `path`s are copyrightable...
Really? Can you even copyright a font? As far as I know, fonts can't be copyrighted, meaning they can be used by anyone without needing a licence. IANAL, but it seems like font users aren't required to comply with attribution and share-alike requirements of the CC licence.