Another idea is to base the logo on a well-estabished one, see below.

I think colors should be added, then the shape changed in a way looks more like Pd. The shape emphasize a duality, just like in pandoc, for any 2 given formats, you (usually) can go back and forth between them (another way of saying $\forall \delta_i, \delta_j \in \Delta, \text{pandoc}_{ij}: \delta_i \rightarrow \delta_j$ )

One possible variation of the shape is the outer border becomes a square, giving a much more distinct yet familiar look.