Well, your opinion is exactly what this is–and it is wrong. There is nothing at all “highly irregular,” or irregular to any lesser degree about our veneration of at least one post-schism Orthodox saint. St. Gregory Palamas is officially venerated by both the Ruthenian and Melkite Catholics on the second Sunday of Lent. This is not a local or private veneration–it is on the actual official calendar. There may be other Eastern Catholics who include him on their calendars, but I know both the Ruthenians and the Melkites do.
Furthermore, I find your comment “Such a practice would be highly irregular and would indicate that ‘conversion’ while officail was still unfolding at the spiritual level,” to be very disturbing. The Eastern Catholics did not “convert” at all when entering into union with Rome. Non-Christians convert. Our various churches came into full communion with the See of Rome, we did not convert. Furthermore, in the future, if some, or all of the Orthodox Churches enter into full communion with the See of Rome, I hardly think that they will be required to give up the veneration their saints who are post-schism. If such a requirement is placed upon them, full communion almost surely will not take place.