I believe it's been suggested that the Scand countries generally use the Norse/Alfar terminology for elves and dwarves. Svartalfar would, actually, probably be in use for the dwarves already, so ... probably not available for Night Ones.
Maybe we'll all just break down and call 'em 'Nightcrawler' the way we're meant to. 
I really don't see a reason for Scandinavians not to call Dwarfs dvärgar/dwarves/dvergene/kääpiöt. Calling someone a Svartalfar might be taken the wrong way. The text about Night ones mention that calling em Dark/Night Elves is consider rude, so I don't think that calling all dwarfs that make any sense.
As for the other two types, imagine we'll see something on them later.
Do people have any ideas what these metavariants might be or where they are from? IIRC The only area that has two metavariens of the same metatype is Greece with Cyclops and Minotaurs metavariants of trolls. So just because there already is a orc metavariants in a area doesn't eliminate the possibility for there being more from the same place. That said
all orc metavariant hail from the Eurasian continent (If you wanna include Japan in that continent) and isn't that a bit boring? Orc metavariants seem to vary a lot, just compare Satyrs, Onis and baseline orcs. That would mean that the people coming up with new metavariants have a lot of flexibility when it come to what exactly an orc metavariant can be.
I hope I didn't ramble one too much here.
