I think it's a mistake to take campaigns like those from starcraft or aom as a model for a historical game like ours. it can be quite awkward to attribute to historical characters narrative roles, including personal drives, flings and fights, character arcs and plot twists.
The main selling point for historical RTS is to give players the chance to reenact big historical moments. Impervim GBOR understood that and introduced their scripted scenarios with effective short videos:
https://youtu.be/9KNsYGoogxY?si=Cn6NvHu8nIb3aOOr
Inside the scenarios, there are dialogues, but they are relevant for the game mostly, not for the story or for narration.