I doubt your turtles have any serious nutritional related disease. Some of the shell characteristics you refer to are normal in young growing turtles, there shells will smooth out with age and at some point will even smooth and slick with enough wear and age. They are simple captive raised and likely have grown at a little faster rate than they would in the wild. The only thing your turtles probably suffer from is average american spoiled, aka slightly overfed.
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Jeff Benfer
gartersnakemorph.com