Cryptanthus is a terrestrial plant, not a semi-aquatic. The best plants for the riparium planters are true marginal semi-aquatics. These plants make the best representation of that kind of environment and they are also adapted to grow with their roots in underwater substrates. There are lots and lots of really good choices for riparium plants.
Putting an upland terrestrial plant in a riparium planter is like using one of those "faux aquatics" (peace lily, lucky bamboo, purple waffle, etc.) underwater in a fish tank.