Nope. As it turns out, her interpretation of the mosaic in question is even more faulty than that. Sts. Praxedes and Pudentiana, which I've had the good fortune to visit, was built by Pope Paschal I in the 9th century. Now, St. Paschal (who obviously was an episcopus!) installed the mosaic in the Church chapel because such was scheduled to hold the tomb of his mother, whose name was Theodora. This alone probably accounts for the Episcopa Theodora in question.
And that's not to mention other obvious things about the mosaic, i.e. Episcopa Theodora is not wearing a pallium and her square nimbus indicates she was alive at the time of the mosaic's completion (nothing more sexy or controversial!).