For my "Cinderella" porthole restoration, I went to a local JoAnns Fabric store and found some upholstery cloth. I took the original cloth with me and found something very close in color. I found the back side of a piece looked closer to the original speaker cloth - so I exposed the back of the cloth rather than the front.
Here are my 2 portholes:
Neither of these are the original grill cloth.
The one on the left (Cinderella, 16") has the back side of a piece of upholstery cloth. The color of this cloth is very close to the color of the original cloth - that is the section that was not exposed to sunlight and faded. The one on the right is a redder color and has some gold sparkles in it. Not entirely pleased with the result, but I think it will do until I get the urge to look for something better.
My speaker cloths are not prominent like you need with your TV. A major part of the look for your TV is the grill cloth. But, I think you may have gotten really close with the samples you found.
Carl