I'm also not sure I entirely understand the problem, but here's another possible (?) approach:

c:\@Work\Perl\monks>perl -wMstrict -le
"use 5.010;
 ;;
 use warnings;
 use strict;
 ;;
 use Test::More 'no_plan';
 use Test::NoWarnings;
 ;;
 my @vectors = (
   [ 'Value:',    '[]'       ],
   [ 'Value:.',   '[][]'     ],
   [ 'Value:...', '[][][][]' ],
   [ 'Value:A',   '[A]'      ],
   [ 'Value:A.B', '[A][B]'   ],
   [ 'Value:.A',  '[][A]'    ],
   [ 'Value:A.',  '[A][]'    ],
   );
 ;;
 VECTOR:
 for my $ar_vector (@vectors) {
   my ($str, $expected) = @$ar_vector;
   ;;
   my $converted =
     join '',
     map qq{[$_]},
     $str =~ m{ (?: Value: | [.]) \K  [^.]*  (?= [.] | \z) }xmsg;
   ;;
   is $converted, $expected, qq{'$str' -> '$converted'}
   }
"
ok 1 - 'Value:' -> '[]'
ok 2 - 'Value:.' -> '[][]'
ok 3 - 'Value:...' -> '[][][][]'
ok 4 - 'Value:A' -> '[A]'
ok 5 - 'Value:A.B' -> '[A][B]'
ok 6 - 'Value:.A' -> '[][A]'
ok 7 - 'Value:A.' -> '[A][]'
ok 8 - no warnings
1..8
[download]