Robin2:
Presumably you are now referring to spoken English rather than written English.One needs to attune one's ears to the local accent. I'm Irish and I was at a business meeting in Texas when one of the experts that we were visiting arrived late due to a delayed flight. Having got used to US accents I could not understand the newcomer for about 20 minutes until I realized he was speaking with a Scots accent. Then there was no problem understanding him.
...R
Years ago we hired a Scots programmer. The biggest problem was not understanding him, it was his use of the middle finger to point to things. Usually in a meeting.
Paul