The Japanese script and text is actually rather mundane. The English version takes stylistic liberties with the old-timey feel and anachronisms. If you got accurate subtitles for the Japanese script you'd see it be much closer to plain, modern English in feel compared to what we're used to seeing. I'd like to have the option of having both- the usual translation and the more accurate one together- but it's too much work for them to do when one version suffices. It also helps keep the base cohesive so they aren't possibly seeing two different interpretations of the same event. Imagine what would have happened if there had been an "accurate" English translation of Haurchefaunt's characterization...

I'm all for seeing the death of script transliterations being masqueraded as accurate subtitles but that's been a problem since anime started being brought over in the '80s. It won't be going away.