First, you really want to use Schwartzian Transform and of course you can check for existence, in this case you check for defined()ness and you must specify the behaviuor: is 'nis-1' greater than 'nis' or less than or what? I assume 'nis-1' and 'nis' must be equal

sub sortHash {
    my $hash = shift;

    [
       map  { $_->[0] }
       sort { $a->[1] cmp $b->[1] or
              defined( $a->[2] ) and
              defined( $b->[2] ) and
              $a->[2] <=> $b->[2]
       }
       map { [ $_ , split /[-,]/ ] }
       keys %$hash
   ]
}
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