Regarding the difficulty of expressing the differing distances of overlapping points in the isometric projection (the one that has four axis) and in the shadow projection. A common way to represent proximity in 3d in a 2d projection is to make the wireframe thicker and/or stronger for closer lines, such as in organic chemistry (see the diagram for Bromochlorofluoromethane [1]), as if the wireframe had non-zero thickness and appeared thicker the closer it is to our eyes

Could something similar be implemented to improve the visualization of 4d objects in 3d projections? Making lines/surfaces thicker when closer in the orthogonal dimension, or changing opacity to represent such thickness

[1] https://en.wikipedia.org/wiki/Bromochlorofluoromethane