Oh, I see I answered this one in How to efficiently find which triangles in a scene might intersect a given triangle? - #2 by michalis 
In short: BoxCollision is not what you need, you have to create what you need (like AllBoxCollisions method I suggest in the linked answer). It can indeed follow some logic of BoxCollision, just not exit early, instead call something (e.g. user-provided callback) for each triangle.
Iām sure you can leverage the existing octree structure to achieve this.
Possibly you can even do this from a unit outside of CGE, imlementing AllBoxCollisions on an octree given as a parameter. Though Iām not 100% sure about this, if need be ā modifying CGE to add AllBoxCollisions also makes sense, and we would welcome such PR