How did Radhakrishnabai demonstrate a lack of devotion by performing the menial task of sweeping Baba's paths?

This is a misunderstanding of the text, which actually portrays Radhakrishnabai's actions as a sign of supreme devotion, not a lack thereof. Chapter 35 explicitly praises her service, noting that even though she was a Brahmin "worthy of worship by all," she personally took up a broom to sweep the paths Baba walked. The narrative highlights that the thought that this service was menial or beneath her "never touched her faultless heart." Her actions are presented as a shining example of humble and selfless service, following in the footsteps of the devotee Balaji Patil Nevasakar. Far from showing a lack of devotion, her willingness to perform this task, as described in chapter 35, is celebrated as a blessed and skillful act of love for Sai Baba.