Everything the ECU needs to run the engine at optimal fuel/air/RPM is on the OBD bus:
Air intake temp, manifold air pressure (MAP), fuel rate, RPM (explanation below), etc. The ECU uses the data on the bus every fraction of a second to run the engine.
RPM from the crankshaft is also used for the speedometer (RPM at the crankshaft, gearing and tire size from the factory = speed)
Whatever comes off a sensor is on the OBD bus and is correctly displayed on the Scanner tool.
If the numbers on the OBD scanner are to jumpy (change so fast that it is hard to read) then the developer should have used a filter. For instance, the engine needs to know the manifold pressure every 1/1000 sec, I don't. The developer should use a filter to just show data every 5, 10, 20, whatever seconds.
The company that developed the tool can say all kinds of stuff they calculate.
For instance, torque, the crankshaft would be the right spot. But the sensor on the crank shaft provides a signal that is converted to RPM (a hall sensor: metal rotating past a magnet of known field strength ... a small current is measured every time metal passes the magnet....etc...) Now the ECU now knows the RPM.
Anyway, as I said: whatever sensor data the engine needs to run perfectly is on the OBD and good information on the scanner tool.