I've attempted to manually correct the issue by moving all the files back to their desired locations and running search/replace operations in the site database. As far as I've been able to determine so far, everything seems to be working at this point, EXCEPT for the software update checks in the backend administration area (screenshot attached). That alone might yet prove to be a serious enough issue to where I have to restore from backups and start over, in which case I'll reply here again and involve you in the process. However, I'm hoping that I can find a fix for that. I've posted a help request on the official Joomla! forums using the same username but so far haven't received any response.
I know it's probably off-topic, but would you guys happen to have any thoughts at to how I might resolve this one issue?