@tegirinenashi as many have pointed out in this thread, there is a lot more variability in composites than aluminum alloys. What I gave were generalized numbers for intermediate modulus Toray T700 UD tape. There are also standard, high and ultra high modulus fibers available... and woven, braid, and chopped fiber! I gave compression strength, because composites typically fail in compression, as they are 2-3x stronger in tension. I was quite conservative in these numbers, to prevent someone from calling me out giving values of a high strength fiber. Strength and stiffness are calculated based on tests in which cross sectional area of the sample is required. So no, it's not based on weight (that would be known as specific stiffness/strength) or volume. It is based on cross sectional area. If you look up a "stress vs. strain curve" you can learn a lot about the strength and stiffness of materials, as well as failure modes.
Yes, composites are anisotropic (properties different in each direction) and aluminum is isotropic. However that is the beauty of composites, you can tailor the layup of the mast to give you the characteristics you want/need. Project Cedrus has no 90 degree fibers in the mast. It is a mix of 0 and 45s. Composites that are comprised of a mix of 0, 90, 45 are known as quasi-isotropic. It's the lazy way to design for composites, and the structure is barely lighter than aluminum when done this way. A properly designed carbon structure should be 30-40% lighter than aluminum of equivalent stiffness or strength. Otherwise it shouldn't exist. Project Cedrus is 40% lighter than most aluminum masts. Solid carbon masts are not lighter than most aluminum masts, because they are not optimized and as you point out likely include 90 degree fibers which are contributing nothing to the design.
Again, foil companies are making solid (or wood/foam cored) carbon masts because it is expensive and challenging to make them hollow. But since they are solid, they need to make them thin otherwise they are very heavy and expensive (more material!). When they make them thin, they lose all the stiffness (and strength).