I imagine there are a few ways to do it, but here's what we do:
SMARTLISTTrigger: "Clicks Link in Email"
Email
contains "[program name]".
Constraint:
"Link Not Contains" unsubscribe.
Constraint: "Minimum number of times"
FLOWHere we set our interesting moments, set acquisition program/lead source if empty, and change the program status to success.
Note: You'd need a separate one of these Smart Campaigns for each engagement program
If it doesn't look cool, you're probably doing it wrong.