but somehow the grammatical “mistake” (using an adjective (Sombre/Dark) instead of a name (Noirceur/Darkness)) works less well in French than it does in English
“Dark” can be used as a noun in English, it’s not strictly an adjective—e.g. “I’m in the dark”. “I looked into the dark”.
“Dark” can be used as a noun in English, it’s not strictly an adjective—e.g. “I’m in the dark”. “I looked into the dark”.