Although one more question, should (@columns-3) maybe be ($columns-3)?

You're thinking of $#columns, which is the index of the last element in the array.

@a = (1, 2, 3);
$count = @a;
printf "\$#a: %d versus \@a in scalar context: %d\n",$#a,$count;
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$#a is 2 versus @a in a scalar context is 3
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