It would be nice to add an announcement if a hearthling is idle for a longer time. This indicates that he got stuck most of the time.
This happened often to me if a hearthling mined too deep and couldn’t get out of the pit. As this takes place under the ground I didn’t noticed it. It is annoying to learn it the hard way (e.g. after an hour wondering why no work is done or when a hearthling died of starving).
The announcement might be something like “Hearthling <name> is idle for some time.”
Another thing I noticed was that there was no announcement when workers were attacked. In this case they digged deep into a mountain and then some wolves appeared in the cave (no “intruders” warning in this case). The workers kept digging but were losing health. I just noticed by luck. An announcement like “Heartling <name> is attacked by <monster>.” would be helpful. In this case I also wondered why the workers kept working. Ok, they ran away but then they returned there to lose more health. Is this intended?