How to read carb calibration chart?

Awsome.
Two suggestions.
1. Tune for best performance. In other words don't worry about the AFR number, much less aim for any AFR number. Use the AFR to see the effect of changes to carb restrictions under various conditions.

2. Ignore this chart. It is wrong.
upload_2020-2-27_15-50-1.png

No idea what it's based on or its just a major editing goof. Doesn't matter. It flies in the face of decades of engine research by industry, academia and the military.

If you want to see a legit relationship of Fuel/Air to engine needs, this one is good.
upload_2020-2-27_16-1-12.png
from Walter B. Larew, Carburetors and Carburetion

More about that graph in Wideband