Interesting...
I had Givi Airflow on many of my previous bikes and it always worked well. On my 2021 GS, after spending money on few screens and spoilers that didn't work (buffeting problem, not wind noise), I decided to make my own Givi Airflow one year ago. So I did it, just like OP had it done. But, it didn't work. The buffeting was a bit better but not solved. So, it was no joy for me. I even tilted all kit towards me by making lower bolts spacers (and new bolts). It was again just a bit better but not solved. Eventually, I solved it with keeping the spacers, installing Wunderlich Marathon screen and adding MRA spoiler on the top. Tested it at max speed and have zero buffeting now.