How to make it work?

I found a workaround. Since nothing worked for me between using that module, implementing a hook in a custom module or even adding rules to the config.js file in the CKeditor library, here's how I disabled the context menu : I downloaded again the ckeditor library from the ckeditor website (ckeditor.com) and customed the plugins list, removing the Context Menu plugin and all the ones relying on it.