As i say in a previous post, Wano/Onigashima is a complety different case of arc. A arc overcharged with characters, subplots, battles, etc. So expecting a quickly deep development on Yamato doesnt fit with the actual rhythm of transition of the series, even the top tiers of Kaido and Big Mom suffers of having a flat personality and participation/motivations (Except Katakuri, Perospero and Queen).
Yamato right now has two paths, stay with the Oden impersonation

or "development" her convictions when she fight with her father or having a serious talk with Luffy. Another optional path its all the Oden impersonation are more deep than "she only reads his logbook" or for her the meaning of being Oden is more relationate with being free, than being a old dead man.