But you have Perl handy so you could:

use strict;
use warnings;

my @puzzle = (
    [3, 1, 2],  [1, 1, 3], [1, 5, 2], [2, 3, -2], [2, 4, 2],  [2, 6, -
+2],
    [4, 6, -3], [4, 1, 2], [6, 1, 3], [5, 2, 2],  [5, 4, -2], [4, 5, -
+2],
    [4, 3, 2],
    );

while (<DATA>) {
    next if !/(\d+)\.\ (\w) -> (\w+)/;
    my ($step, $block, $move) = ($1, $2, $3);
    my $blockIndex = ord($block) - ord('A');

    print "Before step $step $block $move:\n";
    dumpPuzzle(@puzzle);

    my $piece = $puzzle[$blockIndex];

    if ($move eq 'up') {
        --$piece->[0];
    } elsif ($move eq 'down') {
        ++$piece->[0];
    } elsif ($move eq 'left') {
        --$piece->[1];
    } else {
        ++$piece->[1];
    }
}

print "Final state:\n";
dumpPuzzle(@puzzle);


sub dumpPuzzle {
    my (@puzzle) = @_;
    my @rows = map {'.' x 6} 1 .. 6;

    for my $pieceIdx (0 .. $#puzzle) {
        my ($y, $x, $len) = @{$puzzle[$pieceIdx]};

        if ($len < 0) {
            $len = -$len;
            substr $rows[$_ - 1], $x - 1, 1, chr($pieceIdx + ord('A'))
                for $y .. $y + $len - 1;
        } else {
            substr $rows[$y - 1], $x - 1, $len,
                chr($pieceIdx + ord('A')) x $len;
        }
    }

    print join "\n", @rows, '';
}


__END__
 1. C -> left
 2. F -> up  
 3. G -> up   
 4. L -> up   
 5. M -> left
 6. K -> up  
 7. I -> right
 8. H -> down
 9. I -> right
10. I -> right
11. K -> up  
12. J -> right
13. J -> right
14. M -> left
15. D -> down
16. D -> down
17. A -> right
18. D -> down 
19. M -> right
20. H -> up   
21. H -> up   
22. H -> up   
23. M -> left
24. D -> up
25. I -> left
26. G -> down
27. F -> down
28. C -> right
29. B -> right
30. H -> up
31. A -> left
32. D -> up
33. J -> left
34. J -> left
35. J -> left 
36. D -> down 
37. A -> right
38. H -> down
39. B -> left 
40. C -> left
41. F -> up   
42. K -> down 
43. A -> right
44. L -> down 
45. A -> right
46. A -> right
47. A -> right
[download]

Prints (in part):

Before step 1 C left:
BBB.CC
..DEEF
AAD..F
HHMMLG
.JJKLG
IIIK.G
Before step 2 F up:
BBBCC.
..DEEF
AAD..F
HHMMLG
.JJKLG
IIIK.G
Before step 3 G up:
BBBCCF
..DEEF
AAD...
HHMMLG
.JJKLG
IIIK.G
.
.
.
Before step 47 A right:
BBBCCF
HH.EEF
....AA
MMDKLG
JJDKLG
..IIIG
Final state:
BBBCCF
HH.EEF
.....AA
MMDKLG
JJDKLG
..IIIG
[download]

Note that I've changed the puzzle coding to use a top left corner and size/orientation array for each piece and the board size is hard wired at 8.

---

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