Basic Principle: Whenever a check fails or recovers you want to know why. Generally this is either because the site behavior changed or the check configuration changed. Ideally since check configuration can only be changed through the tool, you should be able to record these actions in a journal (you are implementing this already) and be REUSE those journal entries to show these changes on the check overview screen,
There are 2 ways I can think of to achieve this.
1) Either you enable a checkbox when someone updates a check which will automatically write that change as a custom event
2) You view certain journal entries like check reconfiguration as separate to Custom Events. Next to the 'Show Custom Events' button you also show a 'Show Configuration Changes' button that is powered by the journal.
We like the idea. Both ways of implementing them makes sense. Let me get back to you when we have planned this into a release.