Well, the Polish one is no better – sounds as she might be related to this fellow:
Seriously though, I have problems with finding a context in which this sentence wouldn't sound so unnatural… Plural knives make it hard, because you usually only use one at a time. Scissors would indeed solve the problem, but very few people use scissors to cut bread, as far as I know. ;-) In theory it could work as a demonstrative, when pointing toward knives, but personally I would rather use "Ona używa tamtych noży do krojenia chleba" in such case…
Definitely not the best sentence in this course, in my opinion. ;-)
In English it is rare that we use the word "carving" when the action is to cut up food.
The only exception to that is that we may ask another family member to carve up the meat. This may be beef, or turkey, for example. And would only tend to be used at a more formal family gathering. Though it is equally likely these days that we would would use the word to "cut" up the meat even in those situations.
"Carving" is used more commonly for the action of when you are creating an art work. So there is, for example, an art form that specializes in the art of carving food.
Mostly it specializes in carving vegetables.
You can check out some examples of this here on pinterest
Mostly though you would use it if you were carving an artwork in wood, or say, sand stone, etc.