The smiley design makes heavy use of gradients which makes them unreadable at their size and unpleasant to see. See popular social networks for smileys that work (flat or weak-gradient colors).
Freely, permissively licensed options include:
- qubodup’s small smileys | OpenGameArt.org
- needcoffee’s Mostrichgrinser | OpenGameArt.org
- Cubikopp qubic smilies | OpenGameArt.org
I will gladly provide the required resolution, although I don’t know how to replace the entire selection of icon options (I don’t know how much there is).
I’m being subjective of course.