The files are received from the repo listing. If the files aren't in the raw report, that means your tests are running incorrectly. I've used Codecov for many projects and huge teams, no way what you say is true.

Can sonar cloud track coverage based on a specific test suite or language or file path as some repos have hundredth of modules?

I heavily recommend against this advice, because the person can't figure out how to use the tool and claims that source scanning by some third party, is "a good thing", especially after you see the kind of crap sonar agent installs in your CI.