I didn't pick this up until recently, but it was actually released just prior to the final episode of GX. Since it was shorter than the Newtype interview I let it take priority, but I'll finish the other TL in another week or so. Anyway, there's some interesting insight into the characters here. Enjoy.
During its TV airing, Symphogear GX saw only one piece of official merchandise: a single clear file. However, since the series has ended a few companies have step up to provide some generic and not-so-generic merchandise to open your wallet.
Recently there were 2 interviews published in the November issues of Newtype and Animedia. I picked up both of them this weekend and so far have finished TLing one of them. Hopefully I will finish the other one by the end of the week. They offer some good insight into the intentions of the creators and what went on behind the scenes of GX.