If we had such a "very good" understanding they wouldn't be spending billions to build the Electron-Ion collider at Brookhaven. Here's a good article about it, that's much more balanced than the QCD slanted wikipedia article: https://www.sciencemag.org/news/2018/07/scientists-endorse-b...

I especially like this bit about qcd:

> The mess is so complex that even basic properties of the proton remain unexplained. For example, its three quarks account for less than 5% of its mass, the rest arising somehow from energy of the virtual quarks and gluons.