The RPMS which contain only fonts shouldn't be arch-specific. It prevents people from saving download time by re-using the RPMs from alternative architectures. It's even worse when you have to download them a _third_ time because of corruption on some of the mirrors. The mirror on unix.hensa.ac.uk seems to be carrying versions of some RPMS which don't verify correctly.
XFree fonts are per-arch packages because of rpm: there is currently no way to build a sub-package for a different arch than that specified in the spec file. There are no plans to make the rpm BuildArch per-package (rather than per-specfile).