I just realised while reading the new dex that there’s an envelope with scribblings and a print number to the end of the codex.
It took me about ten minutes to translate using the Tau language page but in case you can’t be bothered here it is.
Disciple of Puretide
You are a commander of the fire caste
A hero of the third Sphere expansion
Just two thousand copies of this vital document exist
Use it’s wisdom to enforce unity upon a hostile galaxy
For the Greater good