Updated: Added Djinn's additions.
If Yomotsu-Shikome doesn't fit, then just write in Shikome.
Apollyon should stay Apollyon because that is what the SMT series refers to Abaddon (or his followers) when they are in locust form.
Cronus is correct.
Rarung = Lalung
Nasu = Naiad
Furaie = Erynis (Persona 2 name)
Girimekhala = Girimehkala
Hakuma Boot = Hakuma-Bhuta
Biwahoushi = Biwa Hoshi
Volac = Valac
Jabberwock = Jabberwocky (if it fits)
Fleuretty = Fleurety (most common spelling)
Aim is good.
Inverted Head = Sakasakubi
Body-Conian = Bodyconian
Imtellipperi = Interipelli
V Met = Heavy Metal
Sinful Priest is good.
Friday = Friday 13 or Jason

Jack Lantern could be Pyro Jack because that's what they call him now.
Kurabebi is fine.
Crap Slime is correct.
Saleos = Sallos (more common)
Dan Gui = Tan-Ki is how it has appeared in every English release
9-Tailed Fox is good if it fits

Stanga = Lots of people are used to Stonka
Gremory or Gomory or Gemori. Gomory was the spelling in the SMT2 translation. Gemori is the spelling in Strange Journey.
Huris = Houri
Oonamuchi = Okuninushi
Morgan = Morgana
Kushinada-hime = Just Kushinada is fine.
Disk Knight = Coin Knight. You may not have space for Pentacle Knight
Your elemental slime names are alright.
Raktarango = Rakcarango
Pabilsag as one word is good.
Damballa = Damballah
Tamonten = Bishamonten (if it fits)
Susano-O
Qinglong = Seiryu
Pink Looper
Sludge = Red Slime
Mega Planaria
Sand Looper
Shrunken Head or Demon Head
Laughing Skull = Chatterskull
Bathin = Basmu
Baku BUG = Bug (it's from a movie)
Farai = Bolla
Deva = Daeva or Deev
Valefor = Balaur
Zoma
Bander is Majin Bander
Girtab = Girtablulu
Pooka = Puca
Donn = Gdon or Dawon
Yaksha
Huanglong or Kohryu
Volvo = Volva
Brahman = Brahma