Ok, after days of tinkering I found some random things that finally helped me save both in different ways.
- delete the CurrentVersion.fcpevent file in the project folder in the package contents of the library file
- open FCPX - you'll get an exclamation mark because it can't find it
- close FCPX and reopen it
- one project was selectable and openable; the other was selectable but would still crash after opening
EDIT:
Screw it, I thought I figured a way to open the 2nd project, but it's still crashing. Well at least I saved one of them so far.
Also another weird thing is I closed and reopened FCPX, and the first project suddenly had a different name and it crashed when I tried to open it. After closing and reopening again, it had the original name and I could open it again.
I had difficulty finding anyone online who had the same problem, but if you do, hope this helps.
But after these issues, I am really nervous working in FCP X now. Luckily I had already finished both of these projects and sent them off. But I've been asked to provide a 2nd, slightly alternate version which led me to reopening them. I shudder to think if this happens when I'm still working in the middle of a project(s).