There's a credible argument to support the view that 'Guts' is a poor translation.
No, there isn't. Maybe you should consider taking some Japanese lessons first before criticizing other people's translations and making a fool out of yourself in here.
But anyway, changing the subject now, I must say it's an interesting interview you found there, I haven't seen this one before. Maybe it's a good idea if someone provides a full translation of that interview for the ones that don't understand a word of German? I'd do it, but since I'm not from Germany it will be somewhat difficult for me.
One of the things that caught my interest is that Miura mentions in this interview that he's an atheist and that he personally believes (like he portrays in the manga) that 'God' and the 'Devil' are merely products of the human mind. He also says that he only uses the words 'God' and 'Devil' in a metaphorical sense in his work, and that he doesn't want to limit the world of Berserk by actually introducing a real 'God' and/or 'Devil'. And that this was also the reason - and here comes the interesting part - why he didn't want to include 'Chapter 83' (the Lost Chapter) in the manga.....
Well, I always thought the lost chapter was left out because he thought it gave away too much of the story. So, judging from this new piece of information (for me it is at least), could it be possible that 'Idea' doesn't even really exist at all?