I do agree with what @happycatmachine said. The URL MN is sending for the translation did a bit too much.
However, it is quite strange that this works fine on the iPad version. The iPad version is also sending same URL request with all the parameters. Both the iPad and my Mac has the same region and system language setting. I didn’t log in Google inside MN for the translation. But the Mac version just have different behaviour.
P.S. I’ve tried to log in Google on the Mac version but that doesn’t help.
@Support-Team Please help to look into the problem.