"I am sweeping the bathroom with a broom."

Translation: Ninafagia bafu na ufagio.

[Phmeza]

When is "kwa" acceptable as "with" and when is it not?

[CynW]

"kwa" has several meanings. You're right that one of the meanings is "with", meaning "using". For example: "Ninafagia kwa ufagio" means "I am sweeping with the broom". "na" can also be used in place of "kwa" in this case. Note that "na" and "kwa" have their own other separate meanings so they are not always interchangable. They only share this particular meaning of "using" something.

[Joylyn17]

They should make this clearer.

[AGreatUserName]

You should make your question or comment clearer. I have no idea what you think is unclear.

[juryrigging]

I have a feeling it's sarcasm.