This isn't a Spreadsheet::WriteExcel problem as such. The data_validation() value parameter requires an array ref of values but you are passing an array ref with a single string value:

Something like the following should work:

    my @columnEvidence;

    foreach my $e (@{$xmlData->{columnEvidence}})
    {
        push @columnEvidence, $e;
    }

    ...

    $worksheet[$counterWorkSheet]->data_validation('E'.$counterRow,
    {
        validate => 'list',
        value    => [ @columnEvidence ],
    });

    # Or:
        value    => \@columnEvidence,
[download]

Or skip the accumulation and just use the array ref directly:

        value    => $xmlData->{columnEvidence},
[download]

--
John.