Moin
I think the tags of http://wiki.openstreetmap.org/wiki/User:Aschilli/ProposedRoofLines should get rid of the building: prefix of the roof: tags, as all other roof tags got rid of it also.
OK?
Amiga4000
I would agree with that, but imo you should also try contacting Aschilli - the wiki page is still in his user namespace, so he gets to decide whether we can change them.
Yeah thats my impression, too. If we wan’t to make use of more detailed tags, we need to create a new schema, basing on the current results. But IMHO first we should make sure, that every tool supports the current S3DB schema and than bring up something more complex 
I changed it right after seeing your post