Let me tell you where and how I saw the fireworks a couple of weeks ago while at CBR.
We stayed in Martinique, and while out on the beach looking across the lake, and while near the pool bar, again looking across the lake, over Jamaica, we were able to see fireworks.
So I'm thinking that it is possible to see some fireworks from a room or two (or more) at CBR. But since the fireworks are so high in sky, I wouldn't say that I'm 100% sure of it. I also would think that the rooms on the second floor would have an easier time of it.
Now that I think of it, I have seen people say that they WERE able to see the fireworks from their room at CBR. Next time someone says that, I will make a note of it on my CBR web site.
Basically, any room looking towards the Epcot area *might* be able to see them.
Wish I could've given you a more definite answer! Maybe the Front Desk at CBR would have more specifics.