@jafant yes, the tweeters in the cs2.4 have FF.
I know because I have a slight difference in openness between the two: and Rob Gillum told me that this is either due to some electronic problem (which sparked me to do the upgrade in stead of selling the speakers (I had them on eBay for a day or the, before deciding against getting rid of them..).. I have received my Fluke measuring device yesterday and have still to see if both sisters have the same values), or this may be due to a difference in the amount of FF in the tweeters....
If it's electronics, the problem is solvable. If it's the amount of FF there is nothing to be done...
Y'all have a nice weekend👍🏼
Pieter