Carrot and potato dumplings question

You might try whole wheat pastry flour, too. It's usually used in things like pie crusts, and probably would be the closest in texture to white flour.

Any grain other than wheat will not have the same amount of gluten and thus may have a vastly different texture.

When cooking for for a crispy exterior you want to cook fast and hot. Most dumpling recipes I have seen call for similar ingredients and just about all of them say to boil for about 15 minutes in a broth or soup. If you are already doing this try mixing up the different ratio of ingredients. Cooking it longer will not make it harder with this cooking method.