In Japanese, the letters L and R are interchangeable, e.g. Zelda = Zeruda and Link = Rinku. I don't know what the Japanese name for this alternate realm is, but when I first saw the renaming, part of me thought it may have just been a localization error. This was also partly because personally, I never understood the reasoning for the name Siren World anyways. Sirens are half bird half woman creatures from Greek mythology, famous for seducing men with their songs so the men would jump into the seas to find them and drown. Maybe I just try too hard to find meaning in names, but the name Siren Realm had always given way to a huge flood of crazy ideas that probably are no where near the true purpose of the realm. Silent Realm then does seem to suit the world better. Of course, if the naming was an error, it took a pretty long time to catch it, and given that the game should already be finished, seems like an awfully hasty renaming.
Personally, I like the name Siren World so much better just because it sounds cooler :bleh: