It is 4.50am in the morning here otherwise I would answer you in detail now fully.( I will a bit later)
You need to be copying something like the Skoda Octavia/Superb wiring which had Bulb Monitor and is almost identical wiring to Passat (and has same dash plugs!).
The green Pin 21 is for the headlight
motor monitoring, not the actual bulbs which are wired directly thru relay.
Blue Pin 16 (or 19 - I will confirm) is for brake bulbs (KB from relay) - Octavia/Superb use different pins in this particular case.
I cant remember at this very second which pin KS from relay goes to, but I do have the information.
Do you have a dump of cluster? I can tell you what bytes to change (I think you have the later coding with different addresses)
Graeme