In the OE equipped vehicles, the headlamp washer work only with lights and pressing the windshield washer for some seconds (until the self washing go on). I think your BC is not programmed for headlamp washer so you have to use a retarder relay connected to the windshield washer, as the older vehicles have.
I haven't checked the 159 wiring for the headlamp washer, but if you added all required components and it does not work then it is probably disabled in the Body Computer.
If this is the case then I can try to enable it. I will need a PROXI log from your car and from a car that has this option working.
I've submited my PROXI data to Yani. I'm waiting to sombody submit from his car the PROXI data with headlamp washer jets. I think all cars with OE Xenon lamps has this function active. Thanks.