@MustardBalloon - there is no way to get this data without writing a bespoke plugin. The metadata download infrastructure does not support custom columns, so even if a plugin did scrape exactly the values you want it cannot store them anywhere except in a standard calibre field. And the problem with that is calibre does a collation process involving ISBN pools, Worldcat, and looking up first published dates etc which all combine to guarantee that no matter what value a metadata plugin might scrape for the likes of publication date it won't be that value on the book at the end of the process.
If the publication date of the edition is in the metadata for the PDF, then that can be grabbed by calibre at the time you add the book or via the edit metadata screen. You could then turn off the publication date column in the metadata download options, so that it won't get overwritten. Or just populate it manually.
Anything else like (xth Edition) you can store either in the comments, tags, a custom column or title if you prefer it as others have said. But you will need to do it manually.