Hello Willem,
Thanks for your answer.
I just bought a BCF2000 on Reverb, but it was defective and I returned it. Then I looked for others and the prices were high. On the other hand, at least under Windows, several aspects of this rather old controller made me worry about compatibility. This morning, I decided on an Xtouch One (quite rare themselves today, but found on eBay). I figured what was good for one Berhinger device was good for the other, especially newer ones. On the Nuendo forum, however, it says you have to adopt the MCU protocol.