@SotiCoto
Yeah, sometimes you'll see them use the romaji rather than the "proper" name and that's probably due to TL not knowing that they're demon names. That being said, even the demon names can differ, as one demon can have multiple different ways to spell its name (their names tend to be transliterated from Hebrew or Ancient Greek, which is itself often transliterated from Hebrew). As an example, Asmodeus has many different ways of writing its name. There's Asmodai, Ashmedai, Osmodeus, Asmodee, etc.
Inconsistency in names is unfortunately how things are when there isn't an official romanization and multiple different groups have contributed to the translation over time (as often happens with longer series).