Yeah, I'm surprised the Vatican's quote miners haven't used Theodore before now. He has been in English for some years now.
Theodore is mistaken, which can be seen in 1) he doesn't mention the sixth council at all (which would bring up the issue of Pope Honorius. And the Monothelites i.e. Maronites were a major group he confront in his polemics) and b) his "historical" details do not match what we know from the sources in the Councils themselves. No bishop of Rome called Constantinople I (or had any involvement in it, being out of communion with the bishop who opened it, Abp. St. Meletius of Antioch), Abp. Sylvester of Rome had no involvement to speak of in calling Nicea I, Constantinople II was held over the express objection of Abp. Vigilius of Rome, etc.
Unfortunately, Theodore was willing to twist the truth to make a polemic point, in this case, trying to score an easy win over the Miaphysites.
He goes on on this in a treatise called "On the Councils". A good English translation has been out for years:http://press.uchicago.edu/ucp/books/book/distributed/T/bo3535574.html