Yeah, you are right. It'd be tough to directly modify PDS as that's javascript in a browser and there are strict restrictions on what JS can do on a filesystem in that case.

But maybe someone can create a browser extension that does the same job. Extensions have fewer restrictions so maybe it could be fueled by a file.

Or maybe someone will some up with some kind of shell script that can read the archive and copy & paste the URLs for each of your posts and comments, one by one, into the javascript console of your browser, allowing PDS to take care of the rest (visiting each one and simulating hitting the edit and delete buttons).

The other issue is that PDS depends on old dot reddit dot com currently from what I understand. If that ever gets dropped, PDS will break until it's updated to work with new reddit.