These values originate from the manual - NIOS_8.6_Documentation.pdf
It is less about warning/critical, more about trap trigger/reset. For a warning/critical, you would SNMP poll and warning would be above the reset, critical above the trigger ...
CPU temperature warning threshold/CPU temperature critical threshold - There does not appear to be a Trap for this. ibCPUTemperature is available from SNMP, and there is of course the LOM if enabled (example in doc). I would look at the Intel ARK document for finer details depending on the model of CPU you have.
CPU load warning threshold/CPU load critical threshold - trigger 81%, reset 70%
Memory usage thresholds - trigger 90%, reset 80%
Swap usage thresholds - trigger 50%, reset 30%
