In Australia it’s a well known and cultivated ingredient, and I suspect a lot of people wouldn’t even make the connection to it being the South African slang word without being told. That’s not a common slur here, in a land that has plenty of its own, and if it’s known it’s mostly through television and movies.
There is a quiet push toward referring to it as Makrut now though.
FWIW, as a rough usage survey, asking google from here:
Kaffir lime → About 12,400,000 results
Makrut lime → About 310,000 results
The former is dominated by links to people selling it, including the largest mass-market companies.
The latter by explanations it is another name for Kaffir lime and products from smaller specialty companies.