All the photos I have seen of Cryptocoryne crispatula var. flaccidifolia are of a thin stringy version of balansae. Tropica lists it as the thin form of balansae. The photo I posted looks like a much different species, so I think Dennerle must be mislabelling it.
All the name ambiguity is this hobby is frustrating, especially when you cannot buy any plants locally to see them!