What type of flooring will match my existing Brazilian Cherry engineered flooring?
If it's a floating floor, your best bet is to take it apart, then put it back together mixing in the new boards so they're not all in one spot. 

That said, are you sure the new boards won't match the installed ones? I'm assuming this might be on the edge of a room, so there may not be all that much fading to begin with. 

As for using something else, you certainly could, but you'd likely have to go with at least the same manufacturer to ensure the joints match. And I doubt you'd get a better match than the ones you already have in the box anyways.