Hi Alberto,
In a general Comelit compatibility thread, I just posted my Comelit system: Comelit compatibility - #36 by Davince I have not tried yet to make it work, but think I have found out how to.
It seems to be similar to yours considering the connection of the bus wires. As I understand (from the Comelit thread), the encryption on the bus system requires to go for the analogue set-up. Have you managed to get it working? I am thinking the S-/S+ can be used for ring detection and the opener contacts should be found to solder them to the blue and purple wires of the Nuki opener. Again, I have not tried it yet, so would be keen to find out where you ended up. Thanks!