A lot of different fibres with very different characteristics put together. I’m maybe not the right one to analyse this, but using so many different materials and get them to work together is not the easiest thing to do. At least to my understanding there is not much use to put wood, glass and carbon fibres in the same direction on a spar as they will just brake at different points of bending of the spar.
I have a bad experience of thick wood combined with glass and epoxy. The wood is “alive” and you can not avoid humidity getting into it. The epoxy is gluing the glass so well to the wood that it will brake the fibres when the wood is expanding due to humidity variations.
It would be great if Scarecrow or somebody with more knowledge than me would comment on this.