Kapusta, are you making fun of my drawing? Perhaps I meant to draw a matzah. The matzoh mechitza represents the fact that the CR mechitza is a flimsy thing that can easily break. (Hope I’m not cracking you up)
Back to the point, if a man were to read a book written by a woman, would you consider them to be interacting inappropriately? In general the answer is no, but perhaps if he knows her, knows what she looks and sounds like, it might cause inappropriate thoughts depending on the situation. The CR is a few steps beyond that since there is an actual back and forth, in some ways you “get to know” the other people (or at least think you do until you find out that Joseph is actually a black teenage girl and oomis is a 7-year-old Chinese boy)
The point in the issur of “lo sikrivu” is not to come to inappropriate contact. Daas Torah has told us that socializing can do that. Some might hold that even saying “Good Shabbos” as you pass in the street might lead to that. It depends how far you take the “takana”. Some machmirim may feel that conversing in the CR with someone you don’t know applies here as well. Others will say that since it is mostly anonymous you don’t have any issues.