I've discovered a partial solution from a Creative Cow thread. And in doing so, I've discovered something I didn't know about FCPX.
Here's my partial solution:
I created a new library on the same "problem" hard drive, and created new events with the exact same names as the ones in the corrupted library. Then I closed FCPX. Then I opened up "Show Package Contents" on both libraries and copied everything from the corrupted library to the new library. In my case, the transcoded media alone amounted to nearly a terabyte, so I made aliases of those media files and moved them over.
Voilá. Once I opened up FCPX again, everything I had previously done showed up in the new library intact (including compound clips, synched multi-cam sequences and favorites), but not the projects. The projects never appeared in the new library even when I copied over "CurrentVersion.fcpevent" files from the FCP backups folder. I'm still working out the solution for restoring my project files, but I wanted to report back on the partial solution I've found.
By the way, I did try the 15-day free trial of Digital Rebellion's Pro Maintenence tools. However, there's nothing in there for restoring libraries. I tried it on these projects I can't seem to bring back, though, and although it said it was repaired, it wasn't.
I hope this helps somebody. If anyone has a solution for bringing back my corrupted projects, I'd be grateful.