If you part of your job is to train someone (and communicate with them) and that someone needs to slow down further, then yes, it’s your responsibility to slow down.
it’s bizarre that anyone thinks it isn’t. Can’t imagine ever saying to a colleague ‘oh you don’t understand me. Tough shit. That’s your responsibility.’ I just don’t get people who have never changed how they communicate depending on who they are communicating with. We all communicate with different people, differently.
some of my closest colleagues are Glaswegian. I can understand them, but colloquialisms means somethings are lost, so I don’t use them like I would with friends who live here. And vice Versa. And where some just slip out, we explain them.
op doesn’t seem that bothered that she was barked at, which isn’t ok. She is bothered that she is being expected to change how she speaks. That’s the title and the main part of the op.
and the Op does come across as xenophobic to me. To me it has a whiff of ‘not my problem if that person who isn’t a native English speaker can’t understand me’.
the only resolutions here are
Op slows down
Op tells her bosses she simply will not put more effort in to slow down and training needs to be done by someone else
New employee is let go, because op is offended by having to change how they communicate.
That’s the 3 outcomes. I wonder which one op wants.