They should be called United Statesians in English. I know États-Uniens is the official name in French.
What is it in other langages? How can we promote such use?
Why am I asking? The US administration is currently a disgrace on the world stage, and I am thinking how it unjustly hurts people from the rest of the American continent.
This is a fair question, and I suspect there simply is no generally accepted demonym in English. One could be introduced, but contrast that fairly simple exercise with the replacement of the broadly-recognized demonym for USA residents: “American”. Quickly, it becomes apparent that replacement is far harder than introducing a new demonym, even if the to-be-replaced demonym itself isn’t very logical within the English language.
English is the same language that calls people from Deutschland as “German”, and then American English specifically might also call them “Dutch”, as in, the Pennsylvania Dutch, whom immigrated from Germany. Consistency is not strong in the English language, even over only a few hundred years.