Thanks for adding to the map! I'd suggest you look at the wiki page https://wiki.openstreetmap.org/wiki/Tag:house=terraced. house=terraced should be used if you're tracing each townhome unit separately. building=terrace would be used for the whole building if you're not getting that detailed. If you're going the latter route, it might make sense to use a point to tag each address where the entrance is. Hope this helps, happy mapping!