My point is that sometimes an object does't have a name, and therefore does not need a "name" tag ("Name is the name only"). If an object only goes by some incidental description, then description=* tag can be used instead. In this case it's diffucult to regard "Maasikad Viljandis" as a name, especially if this plural form description is used for an individual sculpture the way it's done here.

As I understand, the idea of site relations is to "group several objects which together have a single identity", and not just group objects that are somehow related or similar. A site relation may group objects that make up an individual bus station, or individual historic site, or alike. I admit you may argue that these sculptures as artworks may somehow make up a group with single identity. But to me it seems more straightforw to compare this group with a category (like a set of lampposts in a city, or a set of bus stops in a county).