Maybe i read the update to fast. I thought every race would be able to make the mask (either early on or later). But if its the undeads racial thing, then its more acceptable.
But

"Multiple masks can be made, and they can even be used by other living characters to disguise themselves as other races, allowing them to approach situations in new ways."

Means that either your main will meet undeads and become their friend (get as a follower) then be able to change faces (by making more masks). Or be able to as a main undead, give new faces to your non-undead friends. Which is strange in itself. Undeads needs the face, but why would a "normal" want to wear a deads face.

And its also strange to transform into other races really :P
if you are an undead lizard, and put on a dwarf face, you turn into a dwarf.
Would make more sense if undead lizard only could wear the face of another lizard :P

But hey, magic :P

if wearing anothers face was only an undeads trait. Then that would make a bit more sense (even if its changing race).

So yeah, im really looking forward to playing, specially the undead. But i deeply hope that there is a good in-game reason for being able to change race, and that living people also can do it.