Your GPU or drivers may have compatibility issues. Different -bgfx_backend APIs may help, you should continue to see the B&W screen when you initially turn on NTSC.

Once that's resolved, you also have to set NTSC A and B to 0.0 and Scanline Duration to 39.1.

The accelerator options are primarily for Total Replay, which enables them when it's decompressing things and then turns back to original speed to play the games. But they're useful for other things too.