Yes, I felt awkward about the gran who posted that she was 'disinterested' in her grandchild. I was sure she meant 'uninterested'.
I have worked a lot with people who have English as another language, and have learned to be careful, helpful, and when appropriate, have a laugh. In some ways it is more difficult working with those who were brought up with English, but sadly, had a poor education. It is obvious that they will be more sensitive.
Sometimes I made a joke by casting myself as 'the old fashioned one' who fussed about things, and joined in with a laugh.
I'm also aware that language changes over time. My kids have recently delighted in telling me that 'literally' can now be used for emphasis, and not actually taken literally!
I have twice recently heard people mis-using 'hoi polloi' to mean stuck up people (I think because they equate it with 'hoity-toity'). The first was on the radio, so I wasn't completely shocked when a friend used it. He is a good friend, so joined in when I said 'you know, that's not how I use that term'.
My favourite, which I do use, was my mother, doing difficult or dirty chores would say she was getting it all done 'in a foul swoop' which seemed quite picturesque!