Or, for a hash-based represenation that's closer to what you originally asked for:

sub parse_brackets {
  my @parse;
  my @stack = \@parse;
  
  my $fewer_indents = 1;   # Try setting this to 0 or 1
  
  my $line_no;
  foreach my $line ( @_ ) {
    $line_no ++;
    $line =~ s/\A\s+//;
    $line =~ s/\s+\Z//;
    if ( $line !~ /\S/ ) {
      next;
    } elsif ( $line =~ s/\s*\{$// ) {
      my @line = split ' ', $line;
      my %node = ( type => shift(@line), ( @line ? ( name => shift(@li
+ne) ) : () ) );
      push @{ $stack[0] }, \%node;
      unshift @stack, do { $node{contents} = [] };
    } elsif ( $line eq '}' ) {
      shift @stack; 
      scalar @stack or die("Too many right brackets at line $line_no")
+;
    } else {
      push @{ $stack[0] }, $line;
    }
  }
  scalar @stack == 1 or die("Too few right brackets at line $line_no")
+;

  return @parse;
}
[download]

Output:

$VAR1 = {
          'contents' => [
                          {
                            'contents' => [
                                            {
                                              'contents' => [
                                                              'Do you 
+like your pie with ice cream?'
                                                            ],
                                              'type' => 'label'
                                            },
                                            {
                                              'contents' => [
                                                              '1 Yes',
                                                              '2 No'
                                                            ],
                                              'type' => 'single'
                                            }
                                          ],
                            'name' => '4B',
                            'type' => 'question'
                          },
                          {
                            'contents' => [
                                            {
                                              'contents' => [
                                                              'Do you 
+like your pie with whipped cream?'
                                                            ],
                                              'type' => 'label'
                                            },
                                            {
                                              'contents' => [
                                                              '1 Yes',
                                                              '2 No'
                                                            ],
                                              'type' => 'single'
                                            }
                                          ],
                            'name' => '4C',
                            'type' => 'question'
                          }
                        ],
          'name' => 'p1',
          'type' => 'page'
        };
[download]

Oh, and for future reference, I don't think I would call this a "macro language". It's a data markup format, with no functional or substitutional behavior.