I think that it might be important to give the "The person who calls himself Taln" comment a little bit of weight.
Obviously, Taln is back, because a desolation has started, and we have this WoB
-Q: What caused a Desolation to end? Was it just the defeat of Odium's forces? Because the Desolations start when the Heralds break under torture.
-A: Because the Heralds can no longer be in existence. There is a certain period of time that they can be there, and after that, if they're there, they will start a new one. So the Heralds do need to leave for a Desolation to end.
-Q: Oh. So they've got a time limit.
-A: They do. Otherwise the Desolation will start again. What they discovered is not all of them have to. As long as one remains, the Desolation will not start again.
But we also have this one:
-Q: Did Hoid switch out the blades?
-A: Hoid did not switch out the blades, but good question.
So, all we really know, is that Taln (must) be back, and also that Hoid (i'm going to take that further and say nobody else either) swapped out the shardblades (which have very different descriptions from WoK to WoR).. So, If Taln in Wok has one sword, and Taln in WoR has a different sword, AND the swords weren't switched.... THEN either the shardblade is an autobot, or its not the same Taln (i.e. if the swords weren't switched, then the man must have been)