Doesn't the data look close to a data structure already? A few regexes and an eval ...

#!/usr/bin/perl

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

local $/;
my $data=<DATA>;
$data=~s{\[}{[qw(}sg;
$data=~s{\]}{)],}sg;
eval '$data=\['.$data.']';
warn Data::Dumper->Dump([\$data],[qw(*data)]).' ';
__DATA__
[
abc
def
]
[
ghi
jkl
mno
]
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and we have ...

$data = \\[
              [
                'abc',
                'def'
              ],
              [
                'ghi',
                'jkl',
                'mno'
              ]
            ];
  at pmdata.pl line 13, <DATA> chunk 1.
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