I'm doing it manually, which takes forever, but at least I know what I am and am not getting. (And it's not like I am actually browsing Reddit, lol, so I have some extra time for deleting). Most of it I was able to do from my profile page, though it only populates 1000 at a time per category, so I had to log out and log back in to get it all. Then I Googled my username, and found a bunch of comments that had been de-linked from my profile (I couldn't see anything there), but were still under my username (anyone could see that I had posted them). Then I clicked through and deleted those.
Now, there are a few still popping up on Google that have actually been deleted, because Google's cache is a little behind the times, but enough are gone that I am not super worried. I'm going to double check tonight before the rollover to July 1, in case a whole bunch of comments come back (a few have over the course of this process, but I just deleted again), but otherwise I am just going to leave the last few until August, when I will do another (hopefully last) round. I don't want to give Reddit any traffic in July.
I don't necessarily recommend doing what I've been doing, but I figure a script is only faster if it actually works the first or second time. I'm not the kind of person who can get that kind of thing to work on the first try, so I decided to just skip that step, crank up my audiobook, and do it in the way I know I can do.