Module is not just code in a separate file. Litmus test: if you cannot have two modules be written in separate languages - you don't have modules. M
If all modules have to be deployed using the same build even though different build of the modules would have been API compatible - you don't have modules.
That sounds way too strict to me. A C++ app might use the C++ ABI to communicate with its modules, which would preclude writing them in any other language without jumping through too many hoops. But that's an ABI constraint and says nothing about the actual modularity of the application.
IMO a module is defined as something that has a self-contained API, and versioning rules for that API if the module is evolving.
If all modules have to be deployed using the same build even though different build of the modules would have been API compatible - you don't have modules.