When you create a PerlTk callback that will take arguments, using the [] syntax, the Tk::callbacks documentation says:

the contents of the [] are evaluated by perl when the callback is created

Therefore, your code,

$mw->Button (
  -command => [\&print_entries, $user_x->get(), $original_y],
);
[download]

my $command_sub;
{
  my $x_at_time_of_sub_definition = $user_x->get();
  my $y_at_time_of_sub_definition = $original_y;
  $command_sub = sub {
    print_entries(
      $x_at_time_of_sub_definition,
      $y_at_time_of_sub_definition,
    );
  }
}
$mw->Button (
  -command => $command_sub,
);
[download]

Instead of telling PerlTk to create the callback, create it yourself with an anonymous sub. This should work for you:

  -command => sub {
    print_entries(
      $user_x->get(),
      $user_y->get(),
      $original_x,
      $original_y,
    );
  },
[download]