Well... my comment was just about the translation notes here.
On the last page, when Yotsuba is making a O_O face, the note says that anyone who wonders why she's making that face should check page 23 of chapter 37.
But on the previous page Yotsuba is told that she should be using kaomoji. On that page there is a note explaining what kaomoji is, together with an example. The example used by the translator is O_O...
So the translator explains about kaomoji and even gives an example on one page. And then on the next page Yotsuba is making the very face used as an example, yet the translator instead tells people to check a previous chapter for the reason.