These images show a few tests, simply by changing the influence of the red and black. I wanted to find a balance where the details of the face can be seen but it is not too over complex and the style is lost.
The black will be edged out in After Effects, so the red could not be too small that it cannot be seen but not too much that it over takes the face as in the last picture. If we are going to render in a similar style then we must be aware of this, and also make it unique for each individual model, as it will be different for each one.
The one thing I must test next is how this will look when two characters are in the same scene and whether they will be opaque or you will be able to see the other character's lines. This also may take into consideration different colours for each character to make them stand out and not merge.