Wow!! I appreciate you taking the time to implement this idea. I tried to download the project from github to give it a go but ran into an error.
calibre, version 2.38.0
ERROR: Unhandled exception: <b>InvalidPlugin</b>:The plugin in u'/Path/to/Plugin/EmbedComicMetadata-read_cix_metadata.zip' is invalid. It does not contain a top-level __init__.py file
Sorry if I jumped the gun and it isn't ready just yet.
Thanks again.