His domain of expertise is nature and fauna, that why he is a gleaner. All the scholar in sharlayan have a domain of expertise not every one of them is knowledgable about aetherology.
Also i feel like those past expansion been about some of the stage of grief
Shadowbringerenial and Anger
Endwalker : Bargaining and depression
Dawntrail : Testing and Acceptance
(That my how interpretation of thing in relation to their last dungeon and zone. Similar but different)