In case anyone is actually following my findings on this, I've created a wiki page for the non-CRF facets of CRF duals including images for all such polyhedra discovered so far. The total now stands at two self-dual and three non-self-dual pairs, totalling eight polyhedra.

Interestingly, so far the self-dual ones are precisely the ones that are chiral.

The names of all of these figures are entirely tentative and were thought up just to identify them - they're not particularly good/consistent names, so any suggestions will be taken on board.

Calculating incidence matrices is what has forced me to work out these cells in the first place (because my verification program insists that I add all the cells and dual cells first), but I haven't yet successfully worked out what the dual of any 4D CRF itself would look like. I find it fascinating though, how the dual of a CRF can have these bizarre-looking polyhedra, and what the entire 4D dual might actually look like!