qfm itself will expand "$mdir" to the name of the module directory when determining the name of the file list. But qfh doesn't do any expansion except in the case where no FILELIST= option is found, when it falls back to the default which happens to match the value that Fedora uses.

So this all works, but if you specify FILELIST= in your configuration (even if it's the default) then "$mdir" won't be expanded and things won't work properly.