My guess would be that the original voice contract wasn't limited to Japan, but rather to Asia. It's not uncommon for Chinese and Korean releases of games to be able to get the rights to voice recordings with absolutely no trouble, but Western releases to have them unavailable.
That's pure speculation, though, as we honestly don't even know if it is a licensing issue that's holding the voices back at all -- only that we were told, in no uncertain terms, that they would not be available for us to use. Which suggests licensing to me, but there's no way to be sure.
And when you're dealing with Japanese businesses and somebody flat-out says "no," you don't go back to them and ask, "but whyyyy?!" -- that sort of thing never ends well.
(Though we can tell Falcom, and have told them, "Hey, people are pretty upset about this decision," which is sort of a roundabout way to be like, "Yo, can't you do anything about this?!")