Good to see you are still as deep in trouble as usual, that means you are somewhat fine. You misunderstand though, I want their services for matters far outside of our borders. Discreet high-profile jobs handed over through several layers of disguises, including the Zaibatsu as 'intermediary'.
I want them to have a most positive picture of the Zaibatsu and establish a communication line through it utilizing my own little network of contacts around here in Kusari. Unlike other actors, I am too cautious to overtly contract these people - you said it yourself and know the reason why it is hard to truly trust them. They are providing overwhelmingly good results so far on tasks provided by these other actors though.
As for what they are doing with these materials, no idea. It is not specified in the contract but seeing as they require the Core and a much longer list than the equipment hauled by Rayne's vessel, it must be something rather complex or huge.