Did Sai Baba himself write the Shri Sai Satcharitra, since the text says 'he makes his own qualities heard by his devotees'?

No, the text does not suggest that Sai Baba physically wrote the Shri Sai Satcharitra. Chapter 36 explains this metaphorically, stating, "the playful Sai himself takes over and makes his own qualities heard by his devotees through someone." This means that the author, or speaker, feels they are merely a pretext or a channel for Sai's grace. The passage in Chapter 36 clarifies this by saying, "making the listener and speaker a mere pretext, he fulfills the desires of the devotees." The authorship is attributed to a devotee who feels inspired and guided by Sai Baba, rather than Sai Baba being the literal author.