Yes, the problem description and desired output do not seem to match. Anyway, here's a GRT for sorting letters then numbers, casting non-compliant lines to the top of the output.

use 5.026;
use warnings;

my @aa = qw{
   CORE1
   CORE12
   CORE8
   duffdata
   CORE233
   COREA11
   COREA12
   COREA130
   COREA12b
   COREA115
   };

say for
   map { substr $_, 54 }
   sort
   map {
       my( $letters, $digits ) =
          m{^([A-Za-z]+)(\d+)$}
          ? ( $1, $2 )
          : ( q{}, 0 );
       pack q{A50NA*}, $letters, $digits, $_;
       } @aa;
[download]

The output.

COREA12b
duffdata
CORE1
CORE8
CORE12
CORE233
COREA11
COREA12
COREA115
COREA130
[download]

I hope this is of interest.