Hello, it’s me:
An update on the problem I posted here:
It seems the problem has to do with the number of active fonts. Fonts can be individually deactivated in Font Book (we’re talking about Macs here), and Cubase Artist 6.5 treats the font as if it weren’t in the folder at all. So that proves that the font isn’t the culprit.
So far, it’s not easy to tell what that “magic number” is before Cubase crashes. It’s not easy to tell how many are active at once. The number at the bottom of the Font Book screen is the total number of fonts, but less than that number can be active. Each font is counted, not just the number of typeface families.
If I ever figure out what number of active fonts Cubase Artist supports, I’ll post it, but it’s a long tedious job to find out! 
And if it helps just one other Cubase user that happens to have at least 438 fonts in his/her library, it’s worth it. 