..one with a cross through is and some writing in French? Obviously roughly it says, "don't leave a child unattended in a bicycle seat" but why is it a picture of a rear-mounted seat - and why in French?

This from the manufacturer,

"Well, it is very funny.  We have had that marking on the child seat for years and no one ever asked why.  The correct reply is that it should not be there at all and it will be eliminated completely.  "