I read that the mosque where Baba stayed underwent a transformation. What do the texts say about this change?

Yes, the texts describe a significant transformation of the mosque. Chapter 5 notes that the year 1912 marked the beginning of an entirely new phase for the dwelling. Before this time, the ground of the mosque was in poor condition, described as having 'knee-deep holes.' The transformation was a direct result of the devotion of his followers. In a remarkable display of service, devotees worked through one night to pave the entire flooring with stones. This act completely changed the physical space of the mosque, marking a key development in its history and reflecting the growing unity of the devotees around Sai Baba.