Hannah – I too would like to know what the Universal Model’s specific stance on this is as well. I can deduce what it may be. First, the Universal Model is most interested in observable evidence through experiments using a universal scientific method which they discuss in the first couple of chapters of Volume 1. Can we observe Dark Matter and Dark Energy? I think the way you formulated your question answers that, “supposedly makes up most of the Universe.” Until it is proven through observation or scientific experimentation then it will remain what it is; a theory.
Volume 3 of the UM, the Universe System, may discuss this in more detail if it is a significant pseudo-theory, a theory taught as fact. I don’t know maybe one of the editors can shed some light on whether it will be discussed in Volume 3.