Below are some loaves adapted to levain without any added yeast. In general, my definitive focal point always seems to be on flour protein and hydration, as fermentation is key to any bread baking.
Wheat and kamut
Definitely more water for this, and going to use lower protein wheat, tweak it.
Sprouted multigrain soaker
A crusty and tight loaf, also more hydration and maybe making a porridge with sprouted grain next try?
Pane di lievito naturale
This loaf has a very firm double fed leavain. In preparing it, feeling it was dry I kept adding water till the dough felt, as heard from a baker years ago, "something between mashed potatoe and soft as your ear lobe." I really need to up the hydro on these dough's again and incoprorate less mixing, less folds, just good long proof and water.