I agree with your point, but I disagree with your conclusion. When Mathilde was acting as purely a master spy, she was spending much more of her personal time to be effective vs when she was acting as a spy-master. The latter definitely took some set-up actions but once we were able to delegate, we had a lot more free time then we used to.
Thematically
The difference is that as Steward we will be a spymaster who employs master spies and very occasionally, in very dire circumstances, goes out to get her hands dirty.
As a Learning Wizard we will be a master spy who employs a spymaster to tell us where we can find things to deal with and occasionally, in dire circumstances, calls in an army to help us.
A Stewardship advisor is expected to sit in an office and organise.
A Learning advisor is expected to ride around troubleshooting.
Both by necessity do a bit of the other but it is not their focus.
Mechanically
Having organisations with lieutenants converts personal actions to organisation actions. Back in Stirland we spent one action on two organisations. That as just a spymaster still in the process of trying to set up our stuff.
Being Steward for a Karak would involve having:
People organising local trade. Inspectors for traders. Local EIC branch. Optional non-EIC traders. Our temple / tavern / adventurer guild. Death Pass patrols, or a liaison for same. Then the Information network itself.
Being Learning Wizard would only need the adventurer guild and information network.
Troubleshooting in person would require more personal actions per turn. But as Steward we would have less personal actions available.
Conclusion
It is a question of if you want Mathilde to spend most of her time delegating or most of her time doing hands-on work.
I prefer the latter.