for manual data the following topic has it all
https://community.tempest.earth/t/sky-vs-co-located-rain-gauge-reporting/5623
for the calibration, nope, I don’t remember such a page but that might be a good idea, I’ll forward to Weatherflow.
Basically there is one done at boot of Tempest or Sky and it needs wind from all sides once at least to adjust the 4 wind sensors.
On server you have 4 : humidity, pressure, UV and rain. Those run on a periodic schedule (though I never ever found the rule). It runs, then double checks the result and if it passes quality control (another secret thing) it will be applied (this isn’t a firmware change, it just happens and it is pretty transparent, except a few extreme adjustments … you don’t notice it)
And last thing that isn’t calibration but related to rain : [raincheck] and also here (Introducing RainCheck)
Hope this already satisfies your curiosity.