Hi Bad_Raven! OSM data can be viewed and edited in lots of different ways through lots of different tools. I’ve not come across “town house” as a specific description in OSM data before…
So we’re all on the same page in this thread, could you clarify exactly what you mean by this sentence? What editor/tool/map are you looking at that tells you they’re “town houses” (is that exact wording used somewhere)? Could you provide a link to the relevant part of the map so other people can take a look at the area?
To partially answer your question, various common values for the building=* key are documented at https://wiki.openstreetmap.org/wiki/Key:building. But that list Isn’t exhaustive – see Any Tags You Like.