Tree::Builder might help:

use strict;
use warnings;

use Tree::Builder;
use Data::Dumper;

my @items = qw(
    Devices_CLI_Inspection
    Devices_CLI_Inspection_L2
    Devices_CLI_Inspection_L2_FilterDatabase_General
    Devices_CLI_Inspection_L2_SpanningTree
    Devices_CLI_Inspection_L2_SpanningTree_MST
    Devices_CLI_Inspection_L2_VLAN_General
    Devices_CLI_Inspection_System_Config
);

my $top = shift @items;

my @items2 = @items;
for (@items2) { 
    s/^Devices_CLI_Inspection//;
    s{_}{/}g;
}

my $tb = Tree::Builder->new();
$tb->add($_) for @items2;

my %hash=$tb->getTree();
print Dumper(\%hash);

__END__

$VAR1 = {
          '' => {
                  'System' => {
                                'Config' => {}
                              },
                  'L2' => {
                            'VLAN' => {
                                        'General' => {}
                                      },
                            'SpanningTree' => {
                                                'MST' => {}
                                              },
                            'FilterDatabase' => {
                                                  'General' => {}
                                                }
                          }
                }
        };
[download]