The source mentions a 'Maharaj' who came to Shirdi. Is this a reference to Gajanan Maharaj?

No, the provided text from Chapter 0 is not referring to Gajanan Maharaj. While the figure is initially called 'Maharaj,' the narrative clarifies his identity. This individual met Chandbhai in a forest, traveled with a wedding party to Shirdi, and entered the Khandoba temple. There, a devotee named Mhalasapati greeted him with "Aavo Sai Baba." The text explicitly states that he held the name "Sai Baba" until the end, confirming this is not about Gajanan Maharaj.