I only have an R1200, but I have never needed to lubricate the windscreen adjuster. With that said, if I want ot adjust the windscreen, I have to stop the bike. The force of the wind against the screen will keep it from moving.
If you try it and it works for a smoother adjustment, please let us know.While moving I never try to adjust the screen up (too much resistance) but I can adjust it down. Recently in the garage I noticed some stutter while adjusting the screen. It occurred only at one part of the full stroke of the shield adjustment: I could hear it, but also feel it in the adjustment knob. Not sure if the source is the gear mechanism or resistance on the rod.