@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
Plus some symbols that resemble the
new hiragana.
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."