The comment action is just there for you to give a description or some info of personal interest inside the state panel, for example if you want to describe what the previous action does or what the current state is for.
If you want to debug variables at runtime you can use any "Debug ..."-Action that fits your variable type, or use "Debug Fsm Variable" to output any given variable in the FSM-Log and optionally also in the Unity Log ("Debug Log" acts like the comment action and outputs it's content as a log).
If you already do use one of those actions and they don't seem to work, then the problem might lie elsewhere.
It would help if you could describe your situation in more detail, say which action you use and what values you insert, or best take a screenshot and show that.
PlayMaker also offers a "Debug" checkbox under the state panel which I find even more helpful than throwing the variables as a log, because you can see directly what values every variable has, even outside Play-Mode (see attachment).
