My perspective is that "const type" order consistently appears in all versions of the ISO C standard and POSIX.

Every major system API I can remember working with that didn't hide const behind a typedef (like Win32's LPCSTR and whatnot) has it const first.

Speaking of Microsoft, though the API's hide const with a typedef, the MSDN samples are predominantly "const char" order.

I've never seen a man page with "int const".

Searching all of the man pages I have installed on an Ubuntu 18 system here (literally grepping through all of /usr/share/man), I found just one with "char const" or "int const". Namely this one:

  $ man guestfs-hacking

This contains:

        int
        commandvf (char **stdoutput, char **stderror, unsigned flags,
                   char const *const *argv)

In the same man page, there are other declarations that have the predominant convention:

        int
        commandrf (char **stdoutput, char **stderror, unsigned flags,
                   const char *name, ...)

You just worked on some unusual code bases, and are glossing over the language and system API's those code bases depended on, and their respective docs.