Among others, it's easy to find major/minor/augmented/diminished chords, or the diatonic chords for any given key (more examples in the "25 Practical Applications of the Tonnetz Chart" video.)
I'm curious about the numbers below the notes, though. They seem to represent the number of semitones above A♭, written in duodecimal (with χ=10, Ɛ=11).
Is there any particular reason why A♭ could have been chosen, or was it completely arbitrary? C might have been a more natural choice, for example.
After @Richard's answer, I tried to update the chart, using C as reference. Work in progress: