This is addressed later in the article. The whole formula is: "3 numbers were inaccurate. I feel frustrated because I keep having to [deal with the consequences]. Would you be able to [double-check all calculations from now on]?"
Personally, I don't get it either. No one I'm frustrated with seems to understand that if I tell them in an unhurried, matter-of-fact way. They may say that they prefer me to express frustration that way, but it gets no results. I don't see the appeal.
The magic of NVC comes from the recipient empathizing with the person making the request.
I genuinely have no idea what this means. What are you trying to say here? So I can be in any feeling except frustration when I'm conveying that I'm being frustrated? This sounds like snake oil.