I understand you have to have some uniquifying string to identify a particular release, whether SemVer, CalVer, CodeName, or something else. I probably prefer CalVer if only because it gives a feel for how old different components of a software stack are relative to one another. Comparing projects with different release cadences is apples and oranges, but at least with CalVer you’re comparing all your apples to the same orange. Otherwise – to me – they are just strings.
But the point I want to make is this: Just because you switch to CalVer for naming releases doesn’t mean you have to throw out SemVer and its benefits (see @mariolenz’s post #13 above). A line in the release notes saying “This YYYY.MM.DD release corresponds to SemVer X.Y.Z” would be enough. Or a line in a meta.yml file like
semver: x.y.z
would suffice, wouldn’t break anything, and still provides the kind of information people use to make SemVer-based decisions.