Your problem seem to be that you nested the file wrong.
Your path should be something like that: .../Dicey Dungeons/mods/morefluff/(all the other files of the mod)
Not: .../Dicey Dungeons/mods/morefluff/morefluff/(all the other files of the mod)
Now the general mod path should be : .../Dicey Dungeons/mods