@sorted = sort {
  my @a = $a =~ /^(.+?)(\d+)#(\d+)$/;
  my @b = $b =~ /^(.+?)(\d+)#(\d+)$/;
  $a[1] <=> $b[1] or $a[2] <=> $b[2] or $a[0] cmp $b[0]
} @unsorted;

##</code><code>##

@sorted =
  map { $_->[0] }
  sort { $a->[2] <=> $b->[2] or $a->[3] <=> $b->[3] or $a->[1] cmp $b->[1]
  map { [ $_, /^(.+?)(\d+)#(\d+)$/ ] }
  @unsorted;

##</code><code>##

use Sort::Fields;

my $sorter = make_stable_fieldsort( '(\d+)#', [ '2n', '3n', '1' ] );

my @sorted = $sorter->( @unsorted );  # voila