Suppress default CSV Serialization Headers and instead use of rich UTF8 Headers

Thanks for your message. This is definitely something we should sort as your examples show its clear this is not ideal. I will start with the reasoning why it is the case but the solution may be a bit more complicated and may need some related issues in the csv_serialization module.

So in csv_serialization, the header is extracted from the keys of the first row:

  protected function extractHeaders($data, array $context = array()) {
    $headers = [];
    if (!empty($data)) {
      $first_row = $data[0];
      $allowed_headers = array_keys($first_row);

That is here in gitlab: https://git.drupalcode.org/project/csv_serialization/blob/8.x-1.x/src/Encoder/CsvEncoder.php#L182.

This answer in StackOverflow explains the restrictions php puts on array keys:
https://stackoverflow.com/a/10696097

So in order to use a wider range of characters, we would need to find a way to to pass our own headers to CSV serliazation.

A related issue where there is a goal to suppress CSV Headers where essentially the problem is the same one (ie, the limitation in CSV serialization):
https://www.drupal.org/node/2854080

At a glance, it seems I have looked into this in the past and it appears CSV serialization has progressed:
https://www.drupal.org/project/csv_serialization/issues/2854087

The problem is, it is not released in the default branch, only their dev branch and beta 2x release. I would be happy to do some sort of check to see if the option is available, or have it as a patch in case you are sure you are using 1x-dev or 2x-beta.

Patch to come shortly with a first shot at this.

This is eventually going to need tests but at least ready for an initial review now.

In order for this patch to work, you will need to be on CSV Serialization 1x-dev or 2x-beta or newer since the default release does not contain the ability to suppress the output of headers.

Updated with a check that setSettings in CSV Serializations Encoder service is public (in default version it is protected).

Pending CSV Serialization change from 2x beta to stable (or new release of >= 8.x-1.5)