Welcome to the forum, @Ian-SAfc.
The easiest way is to use the menu command View > Go to Last Aborted Action.
I believe that In theory, you should also be able to find the relevant action by selecting all macro groups and then entering Action: , followed by the action’s number, in the Search field in the top right of the KM Editor’s window (⌘-F). I say “in theory” because I’ve yet to get that to work! 
Perhaps someone could kindly correct me if I’ve got the theory wrong. I’ve certainly got some aspect wrong…
A quick search of the forum reminds me that one can use Applescript to go to actions based on their ID and that this discussion includes links to a couple of potentially very helpful macros that I meant to try out!