The first error can be ignored: the file size of ttfautohint-1.8.4-3-x86_64.pkg.tar.zst is 1.5M, and the file size of /ttfautohint-1.8.4/doc/ttfautohint.pdf is 1.35 MB.
The second error might be a false positive.
ttfautohint W: Package was 72% docs by size; maybe you should split out a docs package
ttfautohint W: Unused shared library '/usr/lib/libm.so.6' by file ('usr/lib/libttfautohint.so.1.0.3')
There are only two errors left unresolved: