This would be nice to have, especially for backwards incompatible changes. It would also be a good thing for package developers who want to maximize backwards compatibility.
I've found myself needing this today when a test I wrote for Rf_asInteger in R-4.4.1 failed. In April 17th 2024 support for coercing RAWSXP to int was added. Referencing the work in progress API documentation, it mentions that RAWSXP should be supported, but it's a new unreleased addition to Rf_asInteger behavior. So this behavior is not supported for R <= 4.4.1.
I think this would require going through all C-LEVEL FACILITIES sections, and maybe with help of svn blame for cases of undocumented changes.