Never set to 100% convergence.

You might find some elements of this article helpful: Dark is not the absence of light And my earlier article about lighting with Sun and Sky also applies somewhat (its linked in the above article).

You can ignore the bit about SubD and high resolution, its not your problem.

Your problem is that the image is large and there's likely not enough light here to get you what you want. Environment lighting is great, but its not always going to get you to where you need to be. I suggest adding some spotlights to your characters to give the engine more available light to play with.