Why do western translators get Japanese supernatural beings such as Oni wrong.

I've seen time and time again in Japanese anime the usage of supernatural beings being totally translated wrong by westerns. Wheither it be subtitles or dubs there is often wrong termonology. For basics terminology words in Japanese for the supernatural we have bakemono, obake, yurei, yokai, akuma, oni, mazoku, followed by using actual English words like ogre and gobllin. I don't feel like I need to explain the last two as they pretty much mean what they are. Lets start with the terms used specifically in Japanes lore. Okabe means ghost/specture, but it's more tied to the Japanese mythology side of things. Obake is a monsterious ghost or something that is used to be a malevolent ghost. An etheral type beings. This doesn't include demons or devils. In Japanese lore there are many subnames for obake. Then we have youaki which are specific Japanese monsters tied in the occult and can cross over with the term obake. If we speak of youkai, some common ones are Nyurarihon. Anime fans might know this from nurarihyon no mago. Or the if we think of a yokai we can think of the kappa. Now there is a difference betwween teh two. Nurariyon is closer to a spirit type monster of the obake class while a kappa has a more physical body. But Obake is arelatively old term. Now if you hear in anime people calling others or creatures bakemono, its ususally translated as monster. This is someone correct as monster is a being we can't describe but bakemono is taken from obake. Bake = ghost and mono = thing or being. Thus, yelling bakemono is calling someone a monster with no defition or history. THe unknown. They are spectre like and don't have explaination in the human world. As for yurei. Yurei is a very very specific term and it means ghost. However, yurei is only used to describe human ghosts of humans who passed on. As for why I stated how bakemono, obake and youkai are interchangable between the physical and etheral worlds is because again they are from mythology and reside in their own realm and are typically used in Japanese settings. It's rare to see these terms, aside from bakemono, used in a Japanese anime that takes place in a european setting. Bakemono should never be translated as demon or devil as it has zero ties to religious context. Demon and Devils fall under monsters tied to western supernatural beings that have direct correlation to Christainity or a relgiion that has a church. Even if a Japanese anime is in a western setting and there is a cleric that is part of a church calls a creature a bakemono it should never be translated as demon. Now where is where things get a bit confusing. Demon is an English word and used in anime by Japanese voice actors, but when demons often refer to the Western equvilent. Before demon became a common term, akuma was used. Akkuma means devil or demon, but it's more accurate to translate akuma to devil. Akuma is commonly used in things like D. Gray man, Marimashita Iruma-kun and Blue Exorcist. Akuma refers to the typical depection of european devils from hell as depecited in christainity. Akuma have the horns, bat-like wings nad the tail. Akuma can be translated as demon too, but only in the context if it's directly referring to setting of the type of demon used in Christainity such as the beings that follow Satan. Akuma is in a sesnse similar to bakemono is that it is used to describe the occult or supernatural beings that have great fear. THe things that can't be explained. Succubus and others can be referred to as akuma if the anime is tying them to religion. you'll never see western creatures like a succubus be called a youkai. You might see them called a bakemono but their classification is either a akuma or what I'll get into later is mazoku. Mazoku is referred to monsters in a western setting that are not spiritual in nature that part of the physical world that humans live in and akin to other animals. Mazoku takes two terms the ma and zoku. Zoku = tribe and ma is a prefix of the word mahou. Ma + zoku eqquals magical monsters. So it's a monster that is magical. Do not confuse this with youkai as while youkai are supernatural they are not magical. The "magical" that mazoku refers to is i nteh sense of magic like Dugeons and Dragons or things we see in Western fantasy. Things like trolls, orgres, goblins, etc are all mazoku. If mazoku are part of the natural existence of the world then obake, bakemono and youkai are the unnatural. Though mazoku can also be referred to demons but will not be translated as devil. The reason is because it's not tied to Christainity or any other type of relgion. Mazoku can be translated as demons only because of a fantasy setting that has a creatuere called a Maou. Maou can be translated as Demon King or Demon Lord. Intreesting enough Maou cna be translatedc as Magic King. Ma is the prefix to mahou and ou means king. SO Ma (magic) + ou (king) = magic king. In fact anime with demon lords and demon kings has ruined the classificaiton and translation of supernatural beings nad monsters. Usually in fantasy settins with Demon Lords and Demon Kings, it's usually opposed by a country that has ties with a relgious church that worships a god. Because a church opposes the demonlord i feel like Westerners feel like it's easier to just translate all monsters as demons but again this is incorrect. Fantasy has roots in things like Dungeons and Dragons, Tolkin's Lord of the Rings, etc, where little Christain type religous organizations existed. Even in RPG fantasies still keep the roots of classificaitons. I do believe that Japanese words should not be used interchangably If an ogre, troll or goblin is called an akuma or bakemono, this is not their class. If certian monsters are called a bakemono or akuma, it's out of deep hatred and fear because they are akin to a plague. Uncontrollable existences. Thus unless stated so, a Goblin. orgre or troll should never be translated as demon unless general blanket term is akuma. Oni is a monster typically seen in Japanese mythology. Oni is translated as Japanes ogre, but often times we see it translated as demon. This highly in accurate. A oni is a subset of a class of a typeof monser/supernatural being. Translating Oni as demon is wrong. Of course translating an oni as a Japanese ogre is akward but it's better to call them ogre. Unless the setting has a european ogre then oni should just be left as is. Oni is a monster not a demon. The reason for this confusion is that in the Japanese version of hell, oni are the wardens of hell that punish sinners. Hence why western confusion of oni being demons. Oni are a type of monster and should never be called a. You wouldn't call a a Lich a demon. Demon,devil or monster are blanket terms. Lich, Oni, Wright, Troll very specific types. So in wrap up. Bakemono, obake, youkai and mazoku should never be translated as devil. Devil is only used for Akuma. Obake and Bakemono should never be translated as demons. Akuma should never be translated as monster. In English we have blanket supernatural words demon, devil and monster, spirit, ghost. The same can be said to Japanese except they have classes. Obake and bakemono are the closest blanket terms that can be wide reaching. Youkai and Mazoku are not universal though. Monsters, spirits and ghosts that have specific species names should never be translated using a blanket term. Oni is one of those. Youkai is another as Youkai is a subspecies of a broader term obake/bakemono.