It that what it shows in Excel ?

Excel shows Nicholás properly, as does the CSV/text output of xls2csv. But my script, and your test script, both create output with á as á

And, if I open bar.csv in Excel, I get Nicolás

$ cat bar.pl
#!/usr/bin/perl
use strict;
use Text::CSV;
my $outputFile = 'bar.csv';
my $csv = Text::CSV->new ( { binary => 1, eol => "\n" } )
                or die "Cannot use CSV: ".Text::CSV->error_diag ();
open my $fh, ">:encoding(utf8)", $outputFile
    or die "$outputFile: $!";
$csv->print ($fh, ['Nicolás',123]);
close $fh or die "$outputFile: $!";

$ cat bar.csv
Nicolás,123
[download]

I cannot speak to your script as I don't know what's in the input file. But poj's script needs

use utf8;

at the top in order to tell Perl that the content of the source code is encoded as UTF-8. This causes the high character to be read correctly, and the remainder of the script to work as expected.

Note that you will have to consider whether your terminal is set to display UTF-8 when viewing the contents of the output file.

The way forward always starts with a minimal test.