I question as to whether that is technically correct. F2 hybrids occur from a self or cross pollination of an F1. F1 is a crossing of two genetically different plants but Cephalotus follicularis is a monospecific species, therefore technically can F1 exist? If not, then neither can F2. I'm sure any botanists on here will correct me, if I'm wrong.
It is better to simply call them EB x EB. F1 and F2 are usually used in terms of a specific phenotypic charactoristic when crossing individuals with different alleles for a gene or genes (monohybrid, dihybrid and polyhybrid crosses) that cause the phenotype. As the features of EB are not clearly due to a specific known gene or genes I don't think the term should be used.
However, the fact the Cephs are monospecific does not exclude the use of the terms F1 and F2. The term is used for crosses of genetically different individuals of a species, not just crosses between related species. If the features of EB could be attributed to specific gene or genes, then the parents of EB (Dudley Watts x ?) would be the P generation and EB would be a member of the F1 generation, in which case crosses of EB could be called F2 in relation to the genes being studied.
For horticultural purposes, and in relation to EB rather than DW, F2 is not a helpful term, even if techically correct for the DW cross that resulted in EB.