Comfort
When the Bible talks about someone being comforted or consoled, it generally means that they are being offered ideas that will help bring them to a more peaceful spiritual state, whether it is a new state or the restoration of one that had been under attack. It's interesting; we tend to think of comforting someone as an emotional thing, offering our own feelings to help them feel better. But the Writings say that the spiritual meaning of 'comfort' is actually more intellectual, coming when a person gains new true ideas.
In Genesis 5:29, this signifies doctrine whereby what was perverted may be restored. (Arcana Coelestia 531)
In Genesis 27:42, this signifies intent to invert the current spiritual state.
Mouth
In most cases, "mouth" in the Bible represents thought and logic, especially the kind of active, concrete thought that is connected with speech. The reason for this is pretty obvious, but it also holds when people, for instance, remove a stone from the mouth of a well, which represents gaining access to spiritual ideas. The mouth is used for eating as well as speaking, of course. In those circumstances, it represents our first, most external perception of a new spiritual idea or desire. This also makes sense, mirroring the way tasting food in the mouth gives us an instant impression of the quality of the food.