ECUHELP KT200II is confirmed to read and write Audi A6 4G EDC17CP54 Bench Mode.
Look at the ECU of Audi A6 4G EDC17CP54:

Look at this image on how to connect KT200II to the EDC17CP54 on Bench.

Look at the images on reading 100% OK.

KT200II wiring diagram of BOSCH EDC17 CP54 [ 1793 ] – Volkswagen, Audi, Seat, Skoda [Diesel] :
Connect the multifunction cable as follows:

KT200II to read and write use the following driver:
→ BENCH TRICORE
→ VAG
→ TC1793 – VAG
→ EDC17 CP54