You can only build one of each beige building in one city.
How about these? Do they count as "normal" city buildings so you can only build one?
If I was ruling for my group I would rule that you are limited to one cloister in a city region. When it's placed in that region its function is that of a building, so limit of one in each city region.
I understand it is not classified as a building as such, but in that it is classified as each type of tile all at once one of those classifications is a building.