What I actually track in a creator program (and why most brands track the wrong things):
Most brands watch: follower count, likes, reach
I track: engagement rate per post, comment sentiment, repeat post rate, content-to-sales attribution per creator, and which creators repost without being asked
The last one matters more than people think. A creator who reposts on their story without a reminder is a creator who actually believes in the product. Those are the ones worth keeping long-term.
Built 4.5 years of data on this at Crafter's Muse. The program paid for itself.