It's hard to tell. The descriptions of each piece only tell us of a traveller's encounter with the Were-Elk. Considering that the beast is a human that transformed before his eyes, and Anna's mask is already adorned on his clothes, I'd assume it isn't Anna herself as the person just has her mask. (We know from TCoFS that some Terra World's may have just collected her mask after she disappeared admist WW1) My best guess as to why the Were-Elk exists though, is that the belief around the Man Beast of the Red Forest stayed around long enough that Fold Energies created an entity from it, based on the tale shifting from WW1 soliders to nearby townsfolk. That would explain the were-beast aspect of it, a human turned monster in the night, because that might just be how they interpreted Anna and the legends.
