"Metaproject" doesn't capture the idea that I think the author is trying to convey.
An example: suppose you want to improve your French and also build your knowledge of Physics. So in order to target both projects, you attend Physics lectures in French, and also read French Physics books. Thus you progress in both your projects simultaneously.
I would call this kind of thing, "Poly-projects" or maybe "Project complexes". "Meta" would imply one extra level of indirection away from actually doing the project. E.g., thinking about what kind of projects you want to do would be a metaproject.
An example: suppose you want to improve your French and also build your knowledge of Physics. So in order to target both projects, you attend Physics lectures in French, and also read French Physics books. Thus you progress in both your projects simultaneously.
I would call this kind of thing, "Poly-projects" or maybe "Project complexes". "Meta" would imply one extra level of indirection away from actually doing the project. E.g., thinking about what kind of projects you want to do would be a metaproject.