What should I do if the saint I'm devoted to, like Ramakrishna Paramahamsa, isn't in this book? Does that make my devotion wrong according to the text?

The Shri Sai Satcharita does not mention Ramakrishna Paramahamsa. However, according to the principles laid out in its preface, this does not invalidate your devotion in any way. Chapter 0 establishes that the grace of a Sadguru is paramount for salvation, and this Guru can be any figure you connect with, known or unknown, regardless of caste or religion. The text encourages complete surrender and service to saints to gain knowledge. It further states that writing and studying the biography of one's own Sadguru is the most certain service for achieving salvation, affirming that a deep, personal connection with your chosen guide is the correct path.