I prefer Pidgins 1 and 5 as well. I don't really like the eyebrows or the puffy cheeks myself.
For Xue, maybe you could try combining your two propositions? One of them has a big head and little ears, and the other is vice versa. I'm thinking something in the middle would be a good option.
There's something off about ElePHPant to me, it looks like its eyes are bulging out of its head... Do you think its pupils/irises could be made smaller, and its eyes moved around to the sides of its head a bit? I'm also not sure about the angry eyebrows, as none of the other icons have them.
Beastie's eyes also seem a bit close together, and his face seems too tall - his mouth part and his nose could both be squashed upward a bit, resulting in a more circular head. This would also make his eyes sit further down on his face relative to his other features.
I think maybe Tux's beak could be moved further down his face, so it doesn't cover quite as much of his eyes. His pupils/irises also seem too large to me.
Lastly, I think Puffy's eyebrows and half-closed eyelids are a bit too much... Perhaps the eyelids could be removed, and the eyebrows toned down a bit? It might require a bit of experimentation. The mouth and the eyes are pretty far apart vertically, I think the eyes could be moved down the face so that they are just above the mouth (so that they're pretty much halfway down the face). Just as with ElePHPant and Tux, I think Puffy's pupils/irises look too large. The half-closed mouth with teeth showing looks a bit awkward to me, could the mouth be closed completely?
I really like the new Wilber, and Gavroche and Gnu are both very well done! This is pretty nit-picky, but maybe Gnu could be looking less downward, and more straight ahead? I'm imagining what it would look like on the HUD during a race and it seems odd that he would be looking downward.
Something else that may be worth investigating is the removal of coloured irises in the character's eyes. This might reduce the level of detail in the icons and simplify them, but I can't really visualise it myself and it would require some exploration on your part.
Keep up the good work! I hope to see the set completed and used in-game.