Thank you !!
Copied from a post of AFRLme :
Comment sets are random comments the character might say when you try to interact with a scene object or combine 2 objects together, if the action does not exist for the scene object or items. These are for global use, so not all comments/sets will be valid in all situations.
You can create multiple sets, so... you could on mouse over a scene object set a specific comment set to be used for that instance or alternatively if you want to create custom comments for each specific object then create the actions inside of the object & add a display text or narration text action part with custom text.