What were Baba's specific criticisms of the Jnaneshwari that led him to prefer the Uddhava Gita for his devotees' salvation?

The provided text presents a view contrary to your question; it does not contain any criticism of the Jnaneshwari by Sai Baba. In fact, Chapter 18 highlights that the "merciful capable Sainath makes it be read daily in Shirdi" alongside the Nath Bhagawat. The text refers to the Jnaneshwari by its other name, Bhavartha Deepika, and lists it as one of the two main books used for daily parayana (reading) by Bapusaheb Jog. Baba held both the Jnaneshwari and the Nath Bhagawat (which contains the Uddhava Gita) in high esteem for the spiritual upliftment of his devotees.