keys already returns a list, so you could directly assign that to an array and use splice to truncate it:

my @columns = keys $AoH_records->[0];
splice @columns, 10;
$csv->column_names(\@columns);
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If you don't care about truncating the array, you don't even need to save it, since ->column_names() will accept a list as well as an array reference:

$csv->column_names(keys $AoH_records->[0]);
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BTW, on truncating arrays:

• It's also possible to assign to $#columns to set it to a specific length, but unlike splice, this will pad it with new undefined elements if it's shorter.

• The above splice call will produce a warning if the array has less than ten elements. To avoid that, do e.g. this:

  use List::Util qw/min/;
  # ...
  splice @columns, min 10, scalar @columns
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