How can access the Question from its Course when using the E-learning module?
This module creates an hierarchical structure COURSE > UNIT > EXERCISE > QUESTION.

These are entity types connected with each other using an Entity Reference field. You can attach and reuse different units to each course, different exercises to each unit, etc.

So to access the Question from the Course, you follow the "links" that are created via the Entity Reference field. Obviously, for that you must first have entered the data (entity references) for each Question (and its related Exercise), and for each Exercise (and its related Unit), etc.