You could use AA+intentional banding to give the impression of rounder eyes. Adding a shadow directly underneath the eye gives the impression of thick pixels = rounder eyes. If you zoom in it looks more like eye-bags, but at 1-2x it just reads as part of the eye cluster and makes it look a little thicker.
I only edited the humans here. I used the hair colour on Louis CK's portrait because there wasn't a skin tone of appropriate value, but with a 1px thick addition it doesn't matter at 1x anyway. Zoomed in it looks like luscious eyelashes, hah.
I also removed the shadow on the side of Louis's nose because it was reading as part of the eye cluster and taking away from the sad look.