It looks as though that swordplant is doing the same thing that I have seen most kinds of swords do when grown emersed; it's trying to grow its underwater-form leaves.
I have tried quite a few different ones, but there were only three Echinodorus
that did very well in the riparium planters:
- E. cordifolius
- E. cordifolius 'Tropica Marble Queen'
- E. palaefolius "rangeri sword"
You might do better by just cutting the larger leaves off that plant, then planting it underwater. It will probably look real nice as an underwater plant.
Here's a 'Marble Queen' growing real well in my 50G setup...