Apple has updated it's standard Knowledge Base article on how to properly name FCS's Projects and Assets.
Basically it's generally a good idea to stick with "0-9 A-Z a-z _ -" when naming project save files and media files, using anything else may cause issues here and there. I like their three categories though:
Tried and True
Best to Avoid
All the rest
That's essentially AppleSpeak for YMMV.