Reading Johnson's book "The Broken Heart of America"--early on (page 26) he refers to the expropriation of Indian knowledge by the Lewis/Clark expedition. Somehow it struck me wrong. Checking the definitions of "expropriation" and "appropriation" it seems their meaning has been concerning property or assets.
Johnson applies it to intellectual knowledge and intangible assets. To an economist I think the distinction rests on what is "excludable", which intellectual property isn't as a rule. IP is shareable. It's appropriate to refer to the expropriation of land or the appropriation of personal property, but to my mind not appropriate to expropriation of IP or appropriation of culture.
That leaves a question of what label to use instead of cultural appropriation--imitation or emulation or copying, perhaps adding an adjective like "superficial".
A note from a biography of Josiah Wedgwood I'm reading--there's a quotation from an eminent writer in the 1760's pontificating that the classical past (which was being revealed by excavating Pompeii and the tours of Europe by young English men) should be considered the common patrimony of all, so emulation and imitation was fine.