I’m not sure if this has been said before but I have even more proof that Old Man McGucket is the author of the journals (or at least associated with them). In the relatively new episode “Into the Bunker” a laptop is found with the sticker “Property of F” 

In the credits of the episode “Little Dipper” it is revealed that Old Man McGucket’s full name is Fiddleford H. McGucket, which means F is probably short for Fiddleford.

I believe this theory, it’s in my drafts