thanks for this info and your quick response!
I wasn't´t aware of this downside of adjustment layers. I tried your advice with using blend modes. unfortunately the results are very unspecifiec regarding the exact color shifts... at least in this case it doesn´t work well!
I may be wrong, but isn´t there a function in illustrator to edit colors by playing around with the color wheel...?
I really can not understand why HSL adjustments turn vector into rater-images? I mean: vector is the form while colors are just the fill - why does editing the fill is leading to changing the form from vector to pixel? If anyone can give more information on that I would really love to understand the technical background!