The song
無間の鐘 ~ Infinite Nightmare
I see translated as "The Bell of Avici - Infinite Nightmare"
Avici is the lowest layer of hell in Buddhism, in Japanese called 無間地獄
But 地獄 is the part that means hell.
無間 is more like boundless/timeless (無 meaning "without" and 間 meaning a "period" or "section" of time or space)
so 無間の鐘 to me reads more like "The Bell of Eternity"
I wonder if "The Bell of Avici" is an official translation or not
I mean it does say "infinte nightmare" so it's not exactly a happy title, but 無間の鐘 doesnt have any negative connotation to me, rather I find it kinda beautiful and nice
but maybe 無間 has a stronger association with 無間地獄 than with its literal meaning
https://www.youtube.com/watch?v=egpmO6rcK-c