Custom Stories not working...

[Romulator]

That error means that it cannot find the main_init.cfg file, which as far as I know would be in the config folder - or there is an error in it.

Going off memory, since they are full conversion mods (again, memory), I think they are supposed to not be in the redist folder, but in a folder inside the redist folder.

So, the directory would be:
C:/Program Files(x86)/Amnesia - The Dark Descent/redist/tenebris_lake/

COULD be wrong, because I have never installed them.
Other problems could be with your resources.cfg file not being pointed to from the main_init.cfg, or just something wrong with the main_init.cfg folder.