In the anime, it is shown that The Trinity Raven survived the fired Etherion because of Fukuro. But so far, the manga has not shown any appearance of them and neither is the anime itself. There hasn't been any filler arcs in the anime that makes an appearance of them either.
Why are animators revealing that they survived anyway, if they're not ever gonna appear ever again? The manga is said to be almost ending(unless it's not O_O), but there still hasn't been any hints that they will appear in the arc.