That's an interesting factor that I hadn't entirely thought of. While the possibility of someone's train of thought being guided partially by the specific depictions of the shapes did cross my mind, I wasn't certain of whether it would become an issue for anyone.
Showing the picture of the shape after all of the descriptors could possibly fix this issue, and it doesn't sound like it would be too difficult to implement. I also think that the cone drawing isn't one of the best shape images that I created; I had a slight hunch that the curve on the end was a little overly subtle, and your experience seems to second this notion. The fact that you specifically saw a pizza slice makes sense with this.
Thank you very much for the input! I'm glad that the player being involved in writing the narrative worked for you overall.