concerning the writing issue the dialects have never rlly been written languages most arab countries use either standard arabic or french or English, tge dialects are usually only used in vocal communication which explains the appearance of the so called Facebook way of writing darja so tunisian being written in arabic letters isnt even a rule or sth we practice in reality and even if it were that doesnt make it by default a part of the language that has the original writing system(tunisian darja wouldnt be considered french or English just bcz some people write it in thkse characters)