Does it means that the remote content of cd.js is different for each website or is this only the filename which is different? In both case you proposition to let the admin add by itself the expected hash is a good idea.
Regarding the uc.js script, without version control it is not so easy to handle. However, a solution could be to start a versioning of the file with a new update of the WordPress plugin. Each future update of uc.js will increment the uc.js version. This new version can be integrated in a plugin update.
Regards,
