The Catholic Encyclopedia article you cite was written in 1907, by (most likely) an elderly member of the clergy writing in standard Victorian prose form.  I'm sure you realize how quickly standards of prose mutated during the beginning of the 20th century.  In any case, whether or not that particular phrase is vague is rather meaningless.  As I said above, the simple appearance of the statement "if there are antipodes" indicates dissent over the shape of the earth...a flat earth may or may not have antipodes, but a spherical earth *must* have them.