Well, two things need to be considered. First, we've seen in the story that only one was needed to bring her back to life from the spikes- and that only because they let her fall into the oblivion. So it seems like bringing her back isn't that hard based on the story. But according to the game, when Godfrey killed her, three were required, and they couldn't just bring her back right away, which the story implied they could.

So either Godfrey is a better killer than Old God spikes, or something else is different. Perhaps the Val'kyr are weaker now? Possibly the loss of their circle makes retrieving her more difficult? Who knows.

But the second thing that must be considered: There is every chance she can create more Val'kyr. (Probably from the Dark Rangers.) The inconsistencies, like the number of Val'kyr killed, and possibly the strength of the Val'kyr (having created new Val'kyr without the aid of the Lich King), would be well explained by that.

One thing is certain- the timing of the release of this short story is no accident. We are being given just enough time for everyone to read it before the Halloween event. I think we can anticipate that we'll see a lot more development then.