Why substreet and not housename?

Addr:housename, "The house (or building) name that is included in the address."

These are clearly names of the building, and they are included in the address. 
I think the standard housename is preferable to the very niche and unusual substreet.

Personally, I think we should aim to choose simple solutions (which work across countries and local contexts) over more complicated and particular ones.

Thanks for surveying the entrances!