Out of sheer curiosity and some vested interest I had a look around the internet about this.
I've been using iWork08 for years: Pages, Numbers, and Keynote. I'm still on OSX 10.4.11 (Tiger).
There are many links about the SFWordProcessing error in iWorks and they all have one thing in common, it seems to me: this error only affects iWorks users (any version) IF
they are running a more recent version of OSX than mine, i.e., Leopard or Snow Leopard.
This thread Apple Support Discussions
may be of interest to you. To my astonishment this problem which was reported to Apple in 2007 is still unresolved by Apple.
However, if you read down that thread, one or two users have accidentally found ways around it for themselves, which may help you?
To my further astonishment, I've also come across this old MacFixit resource: Keynote, iWeb, Pages crashes in Leopard -- fonts to blame
- written in 2007.
It's been interesting looking into this for you and hope it helps somehow. There's no chance of you backward-grading to Tiger, is there?