using System;

    using System.Text.RegularExpressions;

    public class Example

    {

       public static void Main()

       {

            var input ="[[[\"Bonjour, Ceci est un test!\",\"Hello, This is a test!\",,,0]],,\"en\"]";

            var parse = Regex.Split(input, "\\[|\\]|[^a-zA-Z ],|\",\"|\"|\"");

            foreach(var item in parse) {

                bool result = !String.IsNullOrEmpty(item) && (Char.IsLetter(item[0]) || Char.IsDigit(item[0]));

                if (result) {

                    Console.WriteLine(item);

                }

            }

       }

    }