Hi Damian,
We are doing something similar to this. What we did was create 2 custom fields called Last Interesting Moment & Compiled Interesting Moments. Then every time a lead has an interesting moment, we update the Last Interesting Moment field with the appropriate value and the Compiled Interesting Moments field to append the data. It looks like this:
LAST INTERESTING MOMENTWe already had several Smart Campaigns running to capture interesting moments based on type. In the Flow steps for each one, we added a second step that updates the value of the Last Interesting Moment field to whatever the interesting moment was.
COMPILED INTERESTING MOMENTSWe created a new Smart Campaign to do this.
Smart List
Trigger > Data Value Changes > Attribute: Last Interesting Moment
Flow
Change Data Value > Compiled Interesting Moments > New Value: {{system.date}} - {{lead.Last Interesting Moment}}, {{lead.Compiled Interesting Moments}}
Now the Compiled Interesting Moments field is a comma separated list of the interesting moments with the date each happened.