To me the icons in that picture look like they are part of the attraction system. The left icon looks like you think someone is cool and the right one is more about admiring someone
When it comes to infant quirks, my guess is that they were shown here. There are 3 icons floating around the screen and I think they might be about being cheerful, sleep and crawling.
https://i.imgur.com/EI9DvyZ.png
This is a screenshot from the video about infants update which can be found
here (only the infants bit at 0:35) and
here(full behind the sims livestream, at 15:07)
