Using Text::CSV seems like a more likely way to get it right on the first try. But your idea isn't hard to do:

s{(".*?")}{ my $s = $1; $s =~ s/,/-/g; $s }ge
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You can also replace the regex with something that handles escapes.

Just for variety, here is another approach:

my $in = 0;
s{(")|,}{ if($1){ $in= !$in; $1 }elsif($in){ '-' }else{ ',' } }ge
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