Maximillan is roleplaying to some extent, so take every claim with a pinch of salt.
I asked before, AN said that every settlement, period, has a clinic staffed by one or two shamans who also do other work. Large settlements have a full shrine building with attendants, with dedicated priests to handle the theology and shamans to do the practical work. And then there's the Temple.
We already know some seriously hard decisions are coming up. If we had just 2 more Stability going into the last tax crisis we could have 100%'ed it on the hardest mode...not that I advocate trying that particular stunt again, but it's valuable to keep in mind that for want of 2 Stability we couldn't get the perfect ending(2 less Grand Sacrifices, 1 less Expand Econ to pay for sacrifices, 2 more Holy Sites)
Incidentally, this is probably Chinampas.
In hindsight, the most likely way for the Xohyssiri to learn how to make Chinampas would be to copy it from their Swamp Folk vassals, where rice paddies are the norm.