Here's one way to go to the specified location in each chunk. (NOTE: fetching and replacement are done to end-of-line, since one field is short.)

#!/usr/bin/perl

use strict; # https://perlmonks.org/?node_id=11147864
use warnings;

@ARGV = 'd.11147864'; # FIXME for testing only, comment out for real l
+ife
local $/ = "\f";
while( <> )
  {
  if( /^ (?:.*\n){13} .{24} (.+)/x ) # line 14 col 25 grab rest of tex
+t
    {
    my $replacement = $1;
    # maybe more calculations here
    s/^ (?:.*\n){9} .{24} \K .+/$replacement/x; # line 10 col 25 repla
+ce rest
    }
  print;
  }
[download]