For me, a lighter roast is a better roast for plunger/syphon. And slightly darker for espresso/stove-top. And by the terms light roast/dark roast l mean: lighter roast= lower finish temperature, darker roast = higher finishing temperature. It is difficult to tell by sight what is an espresso roast and what is a syphon roast.
If you cant get quality espresso from it, there may be a few factors. It may not be roasted for espresso, it may be old/stale, the flight may have adversely affected the beans....
Try using it through a syphon/plunger and see how you go