We dumb Americans can figure out what nappies, lorries, (car) boots and spanners are (these words don't exist as such or in those contexts here). Some of us have trouble with jumper vs. sweater, pavement vs. sidewalk and many other words because they already mean something quite different to us. (i.e. a jumper is a sleeveless dress or shift worn over a blouse [not much at all like a sweater] and pavement is the street.) I know a biscuit is a cookie, but many Americans do not.
On the other hand, Mummy vs. Mommy is pretty simple to understand - don't blame the blogger for being upset over that one.
But, if she wants to actually sell books on this side of the pond, she should let the editors do their 'translation'. It could mean the difference between selling ten copies to people who want to read English novels and selling thousands to the (uncultured) masses who want to read novels.
Greg
"Personally, I am always ready to learn, although I do not always like being taught." - Winston Churchill