I'm not sure what to make of this article. It actually seems very hard to draw a clear-cut boundary between the Romantics and the earlier sentimentalism of 18th-c. English literature. And that sentimentalism in turn seems to be heavily influenced by attitudes towards wonder, individuality, metaphor etc. that had developed already in earlier Baroque literature (which was a continental European movement but nonetheless a huge influence e.g. on John Donne, etc. My relevant point is that the early-modern period was truly "modern" in spite of being strictly pre-Enlightenment, but also surprisingly broad and varied). So this whole notion of "the first Romantics" as being somehow revolutionary just seems to be missing the forest for the trees.
Movements and attitudes are not like concepts and inventions.
I think you hit upon the problem of "periodization".