We cannot learn a first language through a print medium. That is not because print is visually processed – sign language is visually processed. We have some ability to learn a second language through print, but we still need other visual aids (pictures, diagrams, acting) more, with and around which we interact in the target language.
This is why I will be trying to act things out or use non-written visual aids as much or more than writing, and certainly much more than translation.
Recent studies of the claim that different learning styles require different modes of teaching presentation indicate that there is no good empirical basis for that claim. See, for example, Brown, Roediger and McDaniel, Make it Stick, and Dehaene, Reading in the Brain: The New Science of How We Read. The latter book points out as well that reading is not “visual” the way images are in the brain.