The arch can be tricky, but you can offset the TWA if you need to.
Dave, our support manager, scooted his TWA closer to the output jack and was able to mount it flat on the downward slope of the arch. We've also seen them off to the side and they still sound great there.
I have a 210ce and find that placing it on the lower bout of the guitar at a 45 degree angle facing down (rear jacks pointing toward the ceiling) works best as far as feed back control and rigidity of placement. Hope that helps!
Check out our Taylor Tips and tricks guide, you'll want the brace to sit as far against the endpin jack as you an get it.
file:///home/chronos/u-15dafd7aa44d3bf54e9fb2fa6ca37138e4cb1235/MyFiles/Downloads/Taylor%20Tips%20and%20Tricks-%20Blog%20Post(1).pdf
Here's the downloadable PDF. https://drive.google.com/file/d/1jULeD-5wzmru_IMPonpQTizeh4t60MFP/view?usp=sharing
Cham Zhao
My Taylor 214 CE has a curved back and i can't find an area where both the suction rails and the sound port are flush against the back. Any suggestions?