"Not much. The language on the door belongs to an extinct people known as Forkrul Assail, who are collectively personified in our Filcra by the persoange we call Errant."
MT (hardback) page 327.
Also, and I might be looking too deeply here, but I thin SE is rubbing our noses in it a little. Frankly, I'm starting to think he's taking the piss and laughing at us.

Why?
Because I think this is indeed another version of K'rul.
Is it me or does this Elder Gods name not seem a little suspicious.
K'rul - Forkrul Assail
Maybe its coincidence.
Quite simply, a grumpy old man.