When localizing (not just translating) you have to take into consideration that maybe there's no literal term on the destination language, so you may have to do some approximation. I'm not talking just about the words themselves. Just look at this case, it's a religious theme. In English, you can write THE Devil or A Devil. They don't mean the same thing. THE Devil is the one in the Bible. A Devil is an evil person, or more usually, a rascal (kid).
Now look at the term in japanese. Is there something in english that conveys the exactly same thing as "Akumajo"? Demon Lord? What is something in English that can picture the epitome of evil, just by being said? The Devil.
About Dog's house or doghouse, isn't it just a matter of use? I think it has more to do with the format of the dwelling than with it being called a building that houses a dog. We associate that format instaneously with a dog, so doghouse. Just like you wouldn't refer to your own house as a lair, although it technically is your lair, because we associate a "lair" with something more mysterious, more decorated or somewhere that's hard to find or enter.