The spatial reasoning on reading code does not happen on the dimensions of the literal text, at least not only on these. It happens in how we interpret the code and build relations in our minds while doing so. So I think that the problem is not about the spatial reasoning of what we literally see per se, but if the specific representation helps in something. I like visual representations for the explanatory value they can offer, but if one tries to work rigorously on a kind of spatial algebra of these, then this explanatory power can be lost after some point of complexity. I guess there may be contexts where a visual language may be working well. But in the contexts I have encountered I have not found them helpful. If anything, the more complex a problem is, the more cluttered the visual language form ends up being, and feels overloading my visual memory. I do not think it is a geometric feature or advantage per se, but about how brains of some people work. I like visual representations and I am in general a quite visual thinker, but I do not want to see all these miniscule details in there, I want to them to represent what I want to understand. Text, on the other hand, serves better as a form of (human-related) compression of information, imo, which makes it better for working on these details there.