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.
The only one country and citizen name used in Japan outside of very formal contexts is ‘America’ アメリカ. You will occasionally see 米 (bei = rice) used in some contexts, particularly with the kanji of another country as an abbreviation for things regarding those two countries (日米野球… Japanese-American baseball…). Finally, you have アメリカ合衆国 which is the formal name and used on paperwork and means something more like ‘America peoples together country’ somewhat literally, but stands in for the US of A. Technically, there’s also 亜米利加 which is the old way to write it phonetically using kanji without really meaning something about the system of government or anything (it’s just a me ri ka).