The text refers to someone as 'Maharaj'. Is this a reference to Gajanan Maharaj?

No, based on the context provided in Chapter 0, the title 'Maharaj' is not a reference to Gajanan Maharaj. The text uses 'Maharaj' to describe the figure who later becomes known as Sai Baba. This is made clear by the sequence of events recounted in Chapter 0, where this 'Maharaj' meets Chandbhai, travels with his family's wedding procession to Shirdi, and upon entering the Khandoba temple, is greeted by Mhalasapati with the words 'Aavo Sai Baba.' The source explicitly states that Maharaj held that name 'Sai Baba' until the end, confirming the identity of this 'Maharaj' is Sai Baba.