> When Europeans or Americans hunt boar, ducks, wild pigs, dear etc is it called "bush meat"?

It'd be called "game meat" or "wild meat". "The bush" is a synonymous term for the wild, and has neutral connotations.

> Bush meat is a racist term concocted by European researchers.

This paper https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7122066/ would suggest that it was just a neutral translation of what people in Cameroon were calling it. Likely just "meat from the wild", which the English would have neutrally called "meat from the bush".