I've got some good news and some bad news.
The good news is that I finished downloading.
The bad news is that it wasn't because the archive was complete. It was because
Panic: Too many URLs, giving up..(>100000)
The good news is that the archive is still quite usable.
The bad news is that many of the longer threads have their later pages missing.
The good news is that if you click the Print button on an archived thread, you should be able to see the whole thing even if much of it is theoretically "missing".
The bad news is that the parts of the forum that you can only view while logged in are missing.
The good news is that those parts are small enough that saving them manually, with the print button and control-S, is actually viable. At least in theory.
The mixed news is that Google Drive says it'll take 2 hours to upload the half-complete archive I've got. It's about two gigabytes, which Google claims should be no problem. I'm not confident it'll actually work, though.
Anyway, I'm going to sleep. If possible, I'll post the archive tomorrow.