On a G5, using my own x86 gnumeric files and testings with files found here :
All files works fine but for lookfuns.xls.
The same errors occurs on x86 with lookfuns.xls (Debian sid/Gnumeric 1.4.1)
It seems to me lookfuns.xls is bad, I opened bug #165801 on bugzilla.gnome.org .
Please add ~ppc64 to app-office/gnumeric
added ~ppc64 to KEYWORDS