FYI, I did ask the Catholic Encyclopedia web editor for permission when the same issue came up probably about a year ago. I didn't get a reply, if I recall correctly. It's worth trying again, but I doubt they have a nice view the prospect of the encyclopedia's content being included in Wikipedia.
If we feel we don't have one, it would be good to get a definitive view on such issues, when they arise, from a lawyer, and then just proceed regardless of what New Advent says (or fail to say).
Larry