Sadly I haven`t seen the film yet, though it`s been on my "to see" list for some years now. A couple of years ago I was watching some films by Neil Jordan, but discovered that "The Company of Wolves" is available in Germany only in a cut version.
As you say that you don`t understand the 18-rating trev, this won`t make it any easier. Normally Germany is more "liberal" than the UK ehen it comes to censorship (as far as I know), but here they unfortunately agree.