We could do 'tested' for cloud images using autocloud. This is kinda contingent on the autocloud API showing up / working, but we might actually be able to do something with fedmsgs now i think about it (though that wouldn't work for initial data prep or async regeneration).
I've implemented this now, including seeding the data by just pulling old messages out of datagrepper. It's in production.
This issue has been migrated to Fedora Forge: https://forge.fedoraproject.org/quality/fedora-nightlies/issues/3
Please continue any further discussion there.