I took a stab at finding it on the infiniti parts catalog, but not sure if I have the right one or not.
https://parts.infinitiusa.com/showAssem ... ly=8139295
I'm thinking they call that the radiator support panel reinforcement, but I could be wrong. Their pictures aren't too great.
What's wrong with the one you have? I'm wondering if you can fabricate another one, or worst case, get one from a junk yard.