Question [Solved] How can I change subscribers name to full name?

Our website uses the comment function exclusively in the members area.

When someone makes a comment, I would like to see the full name. Often the users have abbreviations that make it difficult to immediately identify who they are. I have already tried various methods, but none of them work.
The subscriber name (or author name) should be replaced by First / Lastname.

I had the script developed, but it works.

Maybe it is much simpler.
Where can I find the code to swap the names?
Who can help?

document.addEventListener('DOMContentLoaded', function () {
    // Warte, bis die Seite vollständig geladen ist
    var commentAuthors = document.querySelectorAll('#wpdcom .wpd-comment-header .wpd-comment-author');

    commentAuthors.forEach(function(authorElement) {
        var userId = authorElement.getAttribute('data-user-id'); // Benutzer-ID holen
        if (userId) {
            // Benutzerdaten abrufen (Vorname, Nachname)
            fetch('/wp-json/wp/v2/users/' + userId)
                .then(response => response.json())
                .then(user => {
                    var firstName = user.first_name;
                    var lastName = user.last_name;
                    var fullName = firstName + ' ' + lastName;
                    
                    // Den Kommentatorennamen ersetzen
                    authorElement.textContent = fullName; 
                })
                .catch(error => console.error('Fehler beim Abrufen des Benutzernamens:', error));
        }
    });
});