On top of that, I have encountered several FCPX crashes with Color Finale too (just by opening the project).
And a lot of corrupted thumbnails render while re-importing.
So I finally had to switch back to 10.1.4 (now everything is back to normal, even under the OSX 10.10.3 asked update).
If you have to go down this drill as well, don't forget to make a safe and verbose/extended XML export of your converted-urgent projects before uninstalling 10.2 (since it looks like a significant number of my libraries backups have been updated to 10.2 too).
Some of the big issues I've met might be correlated with my peculiar FCP workflow (which, I have to stress this, had never known a problem before):
— I work with direct import of XAVC-S files mainly
— my original files are not imported into the libraries/local HD but processed over thunderbolt (BlackMagic MultiDock II)
— my project are always made of 50fps clips on 25fps timeline
— I'm under AMD Radeon R9 M295X (iMac 5k)
May the force be with you.