Module's optional field config not imported on install
Optional config is only installed if it has an explicit dependency on a module that is being installed right now. Otherwise that configuration would be re-installed every time you install a module, even if it is something you chose to delete on a specific site.

The downside of that is that there are some grey areas of config that depends on config that depends on a module being installed that isn't found by this. Although that should also work but apparently does not in this case.

As a workaround, you can add an enforced dependency on the paragraphs module on those configurations that aren't being imported, then it should work. See https://www.drupal.org/node/2404447