It would be a whole lot more reliable to see a cargo spoofer return a player defined item and value. Since we have levels of cargo spoofers, this, in increase of Marks, would give you an increasingly large list of possible return values, and amounts.

For example, a Cargo spoofer Mk1, would give you a small list, of semi-expensive items of which you are able to choose a small amount of each item to return value, and you are only able to spoof 30% of your cargo aboard (you are not able to choose which is not spoofed)

A Cargo Spoofer Mk2, would give you a medium list of semi-expensive and moderately prices items, and you are able to spoof 60% of your cargo on board (you are able to choose 50% of cargo spoofed, others are random)

A Cargo Spoofer Mk3, would give you a large list of semi-expensive, moderate and cheap items, and allows you to choose total quantity, able to spoof 100% of cargo on board.

I'm not sure how you are to implement this, but feedback?

While using CS on someone, it gives response in a moment. I think if trader will wait more then 2-3 seconds with cargo spoof answer, pirate will understand that something wrong.. And how manual Cargo Spoofer will deal with two or three scans at a time?

It's a pre-set thing, genius.