You didn't show us what your expected data looks like, but maybe you should try a different data structure (perldsc):

use strict;
use warnings;
use Data::Dumper;

my %data;
my $fsm = 1;
my $m = '';
my $i = '';

while(<DATA>) {
  chomp;
  if (/^INSTANCE:\s+(\S+)/) {
    $m = '';
    $i = $1;
  } elsif (/^MODULE:\s+(\S+)/) {
    $m = $1;
    $i = '';
  } elsif (/^Fsm\s+(\S+)/) {
    next if !$fsm;
    if ($m) {
      $data{'module'}->{$m} = $1;
    } else {
      $data{'instance'}->{$i} = $1;
    }
  } elsif (/^State\s+(\S+)/) {
    next if !$fsm;
    $data{'state'} = $1;
  } elsif (/^Transition\s+(\S+)/) {
    next if !$fsm;
    $data{'transition'} = $1;
  }
}

print Dumper(\%data);

__DATA__
INSTANCE: i_name
Fsm f_name
State s_name1
# Transition t_name
# State s_name2
[download]

Prints:

$VAR1 = {
          'instance' => {
                          'i_name' => 'f_name'
                        },
          'state' => 's_name1'
        };
[download]