So, as of tonight, all but three tier 1 modules from kf5 are built in meta-kf5. The ones remaining are KApiDox, which does not really apply, and KConfig and Sonnet, which both needs to be part built for the native host environment, and part cross compiled. So, any Yocto hackers out there, please have a look at the issues linked to from the meta-kf5 status page.