@ArgonDorn in GTL, machines (notably, the AI that went mad) used these diagrams as language. They were also present in the temple, so humans used them as well.
The diagrams in this specific chapter contain random Japanese words:
タニシ - Viviparidae (river snail)
よもぎ - Artemisia princeps (Japanese mugwort)
うに - Sea urchin
What this all could possible mean?
Well, Chii and Yuu once found the Voyager Golden Record, maybe the diagrams were inspired by them? Good luck decoding that mess in that case.
If I had to guess, maybe it has something to do with this series being called "Shimeji Simulation."