As I said in your previous post, this seems to be about the stability testing of the software system. Stability testing is performed under certain pre-defined scenario, and this scenario for the test is called “test cases.” Therefore translating 項目 as “item” in this context is not appropriate.

策定 can be “designing” or “planning”, but considering the text in the previous post, I think 策定 here could also mean “selection.”

Please refer to the URL I posted in the previous post. I think this document is useful for you to translate current project.