Dimensional difficulties
The main difference between translating between two human languages and translating from spirit communications into physical reality is that the latter kind of translation work is fraught with far more difficulties.
All human languages share many common constructs and concepts (for example, mother, father, birth, death; but also, built into them all, are the inherent recognition of our physical reality and certain commonly shared beliefs about that reality). In the spirit world, there are what you might consider to be expanded versions of those same constructs, plus some.
Thinking of it in terms of dimensions is a very useful analogy. For example, When you have two dimensions, you have only length and width, not depth. Trying to imagine what depth would be like from the perspective of a two-dimensional world might be impossible, or, if possible, it might be possible only in a distorted way. Once you add that third dimension, it seems obvious and a matter of course to you to see what depth is. But try to explain it to your flatlander friends who are still in the second dimension....
Another analogy might be that of the senses. Imagine trying to explain taste to someone who has never had the ability to taste anything. Or smell, touch, sight, hearing, emotions--all of these would be hard to explain, describe, or discuss with someone who didn't have experience with these things.
A friend of mine who is now blind but wasn't at one time once told me of how she was in a discussion once with people who had been blind from birth. The topic was one that probably all of us have played with at some time or another: If you had to give up one sense, which would it be? In this case, the topic was modified somewhat to assume that the people had the choice of four of our five senses. My friend said that those people who had been blind from birth said they would still choose to be blind rather than, say, deaf. They couldn't imagine how sight could be useful--but take away their hearing and they would feel it! Their main argument was, how could you tell you were approaching something if you couldn't hear the various small sounds that echoed from those items or that those items made? My friend found that she could not explain how sight could perform many of the functions that hearing was performing for them, and they remained convinced that hearing was better than sight. (I'm not taking a position here; I'd have a hard time choosing too, if I had to choose, because each sense contributes something uniquely beautiful to our three-dimensional life.)
The channeler experiences a similar difficulty in trying to translate the messages being received in that s/he is still within the world of three dimensions (or the five senses, if you will, ignoring, for now, the fact that there are of course far more dimensions, including time, the fourth dimension), yet s/he is trying to communicate concepts being conveyed from a being who is inhabiting at least one dimension up (the fifth dimension or greater), or whose existence is entirely within the spirit realm (I don't claim to have much knowledge of such; the more I learn, the more questions I have and the less I think I know) and therefore not dependent on physical reality as a reference point, though that greater reality encompasses ours.
Another way to look at it is to think of each dimension as a matrix that includes any "lower" dimension within it. So, for example, the second dimension includes within it the first dimension; the third dimension includes the first and second; the fourth dimension includes the first, second, and third, and so on. If you were a person stepping from dimension to dimension, you would continue to experience each previous dimension, yet from a different perspective. In a sense, you are able to view the previous dimensions as something incorporated within your new dimension; you could almost say that you are viewing the previous dimensions from "outside" them.