Hi Anna,
Creating Fiss charts is not easy, out of the box.
All examples I've seen look very much like manual, customised work, because solutions labels are different from one situation to another.
There is a semi-automatic solution written by Claude Rubinson, but that is not in R. We are thinking about a compatibility framework that would incorporate both R and external tools like Claude's, however this will take some time.
I'll try to think about a temporary solution for this high-demand feature, which will most likely involve some post-processing into another software like Inkscape, since the Fiss chart is essentially a figure (an image, to be more precise), and a vector format like SVG offers the possibility to further modify that image according to particular needs.
All the best,
Adrian