Place garbanzo beans in a small saucepan over medium heat. Cook until soft, 10 to 15 minutes. Drain and let cool. Stir 1/2 cup water and yeast together in a small bowl until yeast dissolves. Let stand until yeast forms a creamy foam, about 10 minutes. Combine lentils, millet, great northern beans, mung beans, and adzuki beans in a high-powdered food processor or blender. Blend on high speed until fine enough to pass through the mesh of a sifter or strainer. Pour lentil mixture into a large bowl. Mix in whole wheat flour, barley flour, and rye flour. Place cooled garbanzo beans in a large bowl. Add honey, olive oil, and salt; mash together. Stir in remaining 4 3/4 cups water. Stir in yeast mixture. Whisk in 2 cups flour mixture. Stir in remaining flour mixture, 1 cup at a time, kneading well until dough is smooth. Grease a large bowl and place dough inside. Cover with a very damp cloth. Let rise until doubled, about 1 hour. Deflate dough and turn out onto a lightly floured work surface. Knead gently and divide into 4 pieces. Form each piece into a loaf. Grease four 9x5-inch loaf pans. Place loaves inside. Cover with a very damp cloth and let rise until doubled, about 40 minutes. Preheat oven to 375 degrees F (190 degrees C). Bake loaves in the preheated oven until golden brown and the bottom of a loaf sounds hollow when tapped, about 1 hour.