Nothing is written to disk until a run is started. The live view keeps working either way. Each run gets its own directory holding the measurements and the events.
Recorded with the wall clock and the seconds since this run started, next to the sensor logs, so it can be lined up with the measurements afterwards.
Noticing at 14:00 that something happened at 13:20 is the normal case, so an event can be backdated - the log is about when things happened, not when they were typed. Enter the clock time it happened, or arm the flag above the live chart and click where it happened. A time later than now is taken as yesterday.
Kept in this browser, not in the reactor's configuration: it is what you want to look at, and the same reactor is watched from more than one machine. Leave both ends of a scale empty and the curve is scaled to what is on screen.
Put the sensor into a known condition, enter what the reference reads, then capture. The raw value is taken from the probe at that moment; "take" copies it into the field where it can be corrected, or typed in from a certificate without the probe being in anything. The mapping takes effect once both points exist, and every change is written to the reactor's calibration file at once.