I've been having trouble sleeping. Does the Sai Satcharita mention if Udi or Baba's grace can help with insomnia?

Yes, Chapter 33 provides examples of Udi and Baba's Darshan helping with sleep problems. In a footnote by R. Hari Sitaram Dixit, he recounts how a friend of his had been unable to sleep for eight days, even with a doctor's medicine. After Dixit gave him some of Baba's Udi to take, the friend reported sleeping very well throughout the night. The same note in Chapter 33 mentions another case of a friend's child from Bandra who hadn't slept for two months. After being taken to Shirdi for Baba's Darshan, the child began to sleep soundly every night thereafter.