500 guy,
As Mitchaa has mentioned, the HUMS in a super puma (any variant ... Unless someone can tell me it's different in a 225) already learns its caution threshold based on data collected over a period of time. When a major component is replaced, most HUMS indicators of that component are put into learning, during this period only the max/red threshold is set (which is a set max from manufacture for that indicator/gear). After a set number of data points are collected the HUMS will set the caution/yellow threshold based on the average of the points collected (ie. mean plus .1 g). The yellow caution will vary for each aircraft while the red threshold is a set number and applies to all.
As far as cockpit awareness, I think Mitchaa has summed it up there as well.