Click on the chart and use the left and right arrow keys to move between terms — a cloud is a single row, so up and down are out of bounds. The terms are walked heaviest first, which is the reading a cloud is drawn for and which its packing spiral does not give in any traversable order. Press B for braille, T for text descriptions, and S to toggle sonification.
Highlighting pairs each term with its own word by matching the rendered text, not by counting glyphs: a cloud writes its words to the SVG in packing order, which has no relation to the order they were declared in.