Is this also regarding this project idea: GSoC 2021 Ideas | Joplin (joplinapp.org) - Paste Special
I guess, HTML part is working fine with this plugin : joplin/packages/turndown-plugin-gfm at dev · laurent22/joplin (github.com)
we have to work on the CSV, PDF.
I think it would be easier to discuss on it if we can make a issue in the main Repo. of Joplin. also, it is easier to implement this with some tweeks.