Maybe this already exists (?) but so far as I can tell when you put in a fermata it goes into the same rhythmical point across all parts. Firstly, I am quite happy that this is the default, considering how many of my students and scores I have to give this feedback to. It’s absolutely true: under normal circumstances, EVERYBODY must see ALL the SAME fermatas.
However, there are points, like this one, where I want - and in fact need - different fermatas in different parts. A simple solution: fermatas could also exist in the playing techniques dialogue and be added individually to parts if desired?