Maybe, but not all hierarchy in the RC have eastern rite parishes and are pastorally responsible fOr them. Was Benedict XVI ever cardinal archbishop for any eastern rite congregations? I'm sure that as prefect of the congregation of the doctrine of the faith, he had to involve himself with the hierarchy of the eastern rite, but this was not done in any pastoral manner.
I'm not sure if Benedict XVI ever had pastoral responsibility over Eastern Catholic communities while he was a diocesan bishop, and as I said before, I don't think it matters either way. Neither he nor Francis were elected based on their experience or lack thereof with the Christian East.
It was simply my observation that, in the immediate aftermath of the election and the rush of journalists and bloggers to find out more about Jorge Bergoglio, one of the "facts" presented was that he was bishop for the Eastern Catholics, and so he had "experience" with the Christian East. That pastoral responsibility, on its own, means very little in terms of familiarity. Supposedly he would visit the Russians on Old Calendar Christmas, is good friends with the new Ukrainian Catholic primate, etc., so there's obviously more to it than just an "on paper" arrangement. But I don't know if it's everything that many RC commentators would have us believe. I don't believe there's a hidden agenda there, I think it's just assigned more importance than it has.
Personally, I think a positive comment about the liturgy is a first, "knee jerk" response to any question regarding Orthodoxy, and given that these were off-the-cuff remarks, so be it (they were beautiful remarks, after all). Perhaps there were "political" or "diplomatic" reasons why he couldn't go beyond that, but I can't help thinking that, in what is increasingly becoming a "post-Christian" Europe, his response to a question about the 1025th anniversary of the Christianisation of a good part of Europe could've been more than, in essence, "They have a cool liturgy, we need that".
That he can say this about the Orthodox liturgy while at the same time allowing his own Church's liturgy to run the gamut, even in his own celebrations, is another matter, but the irony is not lost on liturgically minded RC's.
Along with your question I would ask: what of the Western credentials of Patriarch Bartholew or the other patriarchs?
Since I don't believe "Eastern credentials" are "necessary" for a Pope of Rome, I don't think "Western credentials" are "necessary" for the Orthodox primates. They should know how to do their job at least satisfactorily.