Hi Carlos,
I've managed to create a question prototype that displays two tabs with Ace and allows for editing two separate node modules. The grader is in Javascript, but it could easily be ported to python and consider questions in other languages. Here is simple example on how it looks like:
The prototype's description provides information on how to use it. At the moment, the prototype considers two files, but it could be extended to enable larger number. One glitch I still need to solve is to resize the editor height automatically when changing the height of the response field. The width is adjusted automatically.