There are actually a number of ongoing research projects to establish standards of semantical mathematical representations. Probably one of the best funded running projects (budget ~10MEUR) which has a work package on this topic is http://opendreamkit.org/ . Work is going on at https://mathhub.info/ from my knowledge. I would like to provide a deep link but the site seems to be in a broken state. Apparently people are working on it right in the moment.
Are these projects aiming at something like what I’m describing? Or are they more about something else like verifying proofs?
On the other hand, there are these research projects which however seem to concentrate on standards rather then actually accumulating semantic knowledge.
I would love to see an adoption of hypertext and semantic mathematical notation in scientific papers. Instead of writing $E=m c^2$ in a (LaTeX) paper, we would instead define the symbols machine readably with a code like
set E = physics/Energy
set m = physics/Mass
set c = physics/constants/speed-of-light
I have never seen actual scientific papers which do this kind of stuff, i.e. which are machine readable.The verbalization if most LaTeX commands can help learn to read the equations. Sometimes.