The core had some of the FPU instruction hooks in it that were causing FPU errors (the Mac thought there was a real FPU available). Gunnar removed the hooks and that fixed the issues that did exist. Programs that "require" a FPU can be ran using the SoftwareFPU extension.
When Gunnar puts in the final FPU core, the emulation is going to be insane. It's already testing faster than 8100/80 PowerMac in native PowerPC mode!