Hey, I actually just finished doing research on studies focused on bonobo culture. There has been one major study. I'm going to copy and paste what I have written about this topic from a book chapter I'm working on:

"A study by Gottfried Hohmann and Barbara Fruth in 2003 partially uncovered the cultural world of our other most closely related relative: the bonobo. Inspired by the “Cultures in chimpanzees” study by Whiten et al. (1999), Hohmann & Fruth wanted to know how many of the cultural variants described in chimpanzees were also present within Lomako’s bonobo population. By analyzing behavioural data between 1991 and 1998, they revealed that 14 cultural variants in chimpanzees are also present in bonobos. These include branch drag, leaf sponge, branch clasp, vegetation seat, aimed throw, and the hand clasp (Hohmann & Fruth, 2003). Although the study sample was considerably smaller than the one used by Whiten et al. (1999), this study raised the possibility that chimpanzees were more culturally complex than their sister species (Tennie, et al., 2009). However, future research will still need to be conducted to understand the cultural differences between chimpanzees and bonobos. The results of these studies will likely have deep implications for understanding the emergence of human culture."