Sort what by what?

Your code is too way off for me to decipher your intentions.

If you want to sort the filenames by the substring after the last _, then I'd do something like

my @sorted =
  map $_->[ 0 ],
  sort { $a->[ 1 ] cmp $b->[ 1 ] }
  map [ $_, ( split '_' )[ -1 ] ],
  @unsorted;
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