So just FYI, I'm pretty sure we're reading the subtitle wrong:
We read: "Leifdrasir." This is based on what is shown in the logo.
As it turns out, that "d" is probably not a "d," but rather a "þ": "Leifþrasir." This is from Norse Mythology, from which Odin Sphere is based.
The pronunciation is here:
http://forvo.com/word/leifþrasir/
Listening to it, the Japanese katakana now makes a lot more sense: "Reivusurashiru."
Listen to the pronunciation of the Japanese via Google Translate:
http://translate.google.com, throw in レイヴスラシル and hit the pronunciation button.
Then, you have them actually writing out "Leiftrasir," with a "t," in the trailer, which I'd initially thought was a spelling error (Atlus spelled "Character Design" as "Charcter Design" in the Persona 5 trailer). But looking at it now, it makes more sense as the English spelling for Leifþrasir as it sounds more like the pronunciation.
Anyway, probably an over-analysis here---Leiftrasir is probably the right spelling. But just thought I'd provide it regardless.