Indeed it could be seen as complicated and challenging. The Midsummer Marriage works in America and is not easy to listen to, hence it is not very popular. I have found that your style has not really changed since around the 70's. Between 1966-76 that body of work more or less has an identifiable style, changes can appear normal. Here subject matter is the source of inspiration for work.
Subject matter is the primary source.
I almost write with a story, pictures, etcetera. Trademarks in your music include the extensive use of alternating 4ths and 5ths. Certain pieces do and others don't. In La Belle there is very little. It is important in dance music which requires abstract rhythmic style.