First of all, great job on being able to convince more students on taking the Master degree on Macroeconomics. That is certainly a commendable achievement!
With regards to your question as to whether this is a good anecdotes on convincing people, the story indeed is a bit different than the typical ones expected by the consulting firms. I would try to use other examples which involves direct confrontations and actions from yourself in managing the conflict as well as convincing the other party if you have any.
Even if you decide to use this story, there are several things to be mindful and made clearer beforehand. Note that the the story you mentioned carried 2 risks that might not make it suitable for the traits the interviewer looked after on the convincing experience question:
- Direct conflict and active actions taken by you to convince the opposing sides
- Confusing correlation and causation in the case of indirect results as the example you provided
On the first point, you need to describe in details how your formulated the courses, perhaps taking into account the elements that would likely convince students to become attracted to the field, and what aspects of the courses were designed to produce such results. In this case, the result is not happened arbitrarily, they were meticulously planned.
On the second point, following the lack of clarity on the first point in your earlier description, you might run a risk that the interviewer sees that you are unable to differentiate if you are the primary element that drives buy-ins from the students, or other factors might play into the equation, such as recent surge in jobs requiring macroeconomics background. A consultant's role is exactly to affect an outcome by modifying its key drivers, differentiating causation form unrelated correlation is a crucial pre-requisite.
Hope it helps.