Do you put anything under the clamp on the carbon to protect it? In the past I've tightened brakes on MTB handle bars to much and wrecked them so I'm wondering.
Carbon compound can definitely help. As the following link points out, it helps you avoid 'over torquing' to ensure that the component doesn't slip.
In my personal domain, if there is carbon and carbon, or carbon and some other material, thou must use fiber grip. And a torque wrench. No questions.
There's no need to treat the underlying carbon before installing a clamp-on front derailer. Fiber Grip or a similar assembly compound helps increase grip under lower torque, but this does nothing to prevent you from over-tightening the bolt and crimping the tube. A torque key and patience are required for that.
I recommend picking up a pre-set torque wrench like this:
Example is from https://www.amazon.com/Ritchey-5Nm-Multi-Torque-Key/dp/B009F93S9C but many bike shops have similar tools.
It's small enough to fit in a saddle bag and I bring it with me on rides in case anything slips and needs re-tightening.