Quite easily

my $grammar = <<'__END_OF_GRAMMAR__';
{
   use strict;
   use warnings;

   sub dequote {
      local $_ = @_ ? $_[0] : $_;
      s/^"//;
      s/"$//;
      s/\\(.)/$1/sg;
      return $_;
   }
}

parse      : '(' item ')' /\z/        { $item[2] }

item       : value child(s?)          { [ $item[1], $item[2] ] }
           |       child(s?)          { [ undef,    $item[1] ] }

child      : CHILD_NAME '(' item ')'  { [ @item[1,3] ] }

value      : NUMBER
           | IDENT
           | QSTRING

NUMBER     : /[1-9][0-9]*/
IDENT      : /[a-zA-Z][a-zA-Z0-9_]*/
QSTRING    : /"(?:[^"\\]|\\.)*"/s     { dequote($item[1]) }
CHILD_NAME : /:[a-zA-Z][a-zA-Z0-9_]*/ { substr($item[1], 1) }

__END_OF_GRAMMAR__
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Untested.

Update: I just noticed the "value" is optional. Fixed.

Update: Tested. Found a few bugs. Fixed them.

use Data::Dumper;
use Parse::RecDescent ();

my $parser = Parse::RecDescent->new($grammar)
   or die("Bad grammar\n");

my $parse_tree = $parser->parse($text)
   or die("Bad text\n");

print Dumper $parse_tree;
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