What's wrong with my technique in this Belgian Liège Waffle recipe?
the amount of flour is likely the culprit.  Flour is very sensitive to moisture and can change volume a surprising amount so that the two cups may not be two cups.  Also make sure you are not scooping the flour out with your measuring cup,  but filling it with another implement before leveling off the top with a straight edge.
As you are after a not-quite-bread-like consistency, even though you are using high-gluten flour (in the bread flour called for) you don't want a full bread-like texture
Letting the yeast rise
Many sweet breads do something similar.  Cinnamon buns for example.  It again affects the crumb and texture of the final product.  It also slows down the yeast as it notes in the recipe when you refrigerate for just a little bit.  The rise the next morning should give you nice small bubbles.