RegEx is working in mAirList, but the ^ charakter for every expression is needed.
I wrote up some examples here:
Another (easier) way to get the results: In the Music Block just use soft Attributes for an entry. Set up both values for your attribute and set both of them to 50 (Percent). Or change it accordingly to your needs.
mAirList will select the amount of items like you need for the rotation.