The infernal dictionary is made by occultists/atheists like Aleister Crowley and their Demons are likely Pagan/Gnostic Gods that have their names twisted into Demonic names. There are even reports of people summoning these things and got something that looked completely different from what's shown on the book.

I've even talked about it here a while ago (what if the Demons in the Ars Goetia dictionary are Gods from fallen Jewish tribes? or something like that) and I get comments about how the whole thing is somewhat inaccurate.