Here's a quick pass in Lightroom.
I didn't do much to the face shadows. But if you use Lightroom, I think a combination of the brush tool with exposure, shadow, noise, highlight, contrast, saturation, and noise adjustments should be able to recover quite a bit from the face shadows.
My personal opinion is that the overall is more important than a few mistakes. You've got 23 people in the shot and most look good. But it is true that some client's might be unhappy with this.