Sorry, but I think you can do better. The photo shows what I go through to line things up and get them as smooth as possible. The Red lines are where I've already "snipped" using the Snip Off tool or where I intend to snip. As you can see I use sectional track for the important parts and then cut curves and straights after I line things up. It takes some finesse, zooming and a lot of trail&error.
In this case, the first thing I did was fix the bridge because AFAIK the track separation over the bridge is 4.5".
I then removed the curved stuff and added straights.
I added the O72/O54 curved switch with O72 and O54 curves attached.
I moved them around until they matched the straights so I could snip them. This is where you have to zoom in enough to be able to see both ends and where the tracks overlap.
Here's the end result. As you can see, I went off the table, but one side can be extended and the other side reduced to compensate as long as the entrance remains wide enough.
Another alternative is to use O42 curves to stay within the existing baseboard.
All that said, I have no experience with the curved switches. I've read some say they are troublesome and others say they work fine. I did like that you didn't try to make the inside bottom tracks concentric. The example Jan posted was just to show how dual mains could work, but there is no reason to limit your thinking to everything being concentric around the entire layout. And many folks use flex for straights so they can add gentle curves vs long straight runs for a meandering effect like it is in reality.
