To answer your second question, just normalize the input first. s/,(?=\S)/, /;

Your first question ... I'd rewrite it as so:

foreach my $name ( @names ) {
    my @n;
    foreach ( split ' ', $name ) {
        # Go through each item, push'ing onto @n
    }
    $name = join ' ', @n;
}
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At that point, @names has been modified in-place using aliasing.