Unfortunately that won't work if any string holds "({" or "})". You need a slightly more sophisticated pattern. Below is one way of writing it.

  my $quote = qr/"[^"]*"/; # Naive
  s{\G((?>.*?(?:$quote|(?=(\(\{|\}\)))))*?)\2}
   {$1 . ($2 eq '(\{' ? '[' : ']')}eg;
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You didn't have it in your pattern, and my pattern is based on your, but you should replace "})" with "]," if it shall become a list.

ihb