I too would say it's not the trans, both of my failed trans exhibited slipping and clunking, never a single code.

You check all wiring from TCU, and check TCU in passenger footwell to make sure there's no water or corrosion?

Don't even think twice about going manual with a bad back. I got this car so that I could paddle shift, clutches are a nightmare for my bad back...

Do you have a full vagcom reader, Ross-tech brand software? Do a full scan with details...