Cynops morphs rarely stay in the water through choice and will, in most cases, need a terrestrial phase. When you say landforms what exactly do the terrestrial ones have? They will need hides and cover to make them feel secure – insecurity may lead to stress and non-feeding. The behaviour of aquatic pre-morphs and terrestrial morphs is often quite different. An animal that will boldly snatch at worm in the water may be terrified of them when they emerge onto land. What food items are you feeding them with on land? I would try moving the terrestrial ones to a soil based set-up with a small water dish. Give them lots of hides and provide them with small live prey items. For example: lesser waxworms, small chopped earthworms, live blackworms, tropical woodlice, hatchling crickets, spring tails and fruit flies. Frozen foods may not be accepted by new morphs.
Good luck.