You could use the actionhistorydb: Actual action start and end time
Alteratively you could just change the Fixlet you use to modify this so that the Fixlet tracks changes. In other words, have the Fixlet write its own history.
Lets say the Fixlet currently makes a registry key under
You could have the Fixlet also create a key called
HKLM\Software\MyCompany\MyProperty\History and then under that you could make a key named after the action ID and then it could make several values under that key called,