No automated tests.
Now that the functionality is starting to settle, add automated tests based on the user interface. The underlying API is already tested in core, so we need to test the UI. Test at least one non-entity based config, I think testing both the site info page and the user settings page would be great (since the user settings will be comprised of two .yml files). Plus testing one config entity like contact category or vocabulary (or if feeling ambitious something like a View would be great). But views don't have good schema support yet.
I think testing the config entity stuff should be postponed on further completion of the translation tabs issue, but tests for the site config editing page, that is pretty much at its final place (I believe). So starting with that as a first step would be great.