Another important point is that if our servers are proper PipeWire clients they can enjoy PW benefits like running servers at different sampling rates. I think it is the case now that the whole JACK environment is treated the same and whatever process first starts it sets the samplerate for all that follow.
Another big long-term improvement for both JACK and PW would be to have sclang interface directly with the respective systems as a client so that you can query the graph, subscribe to and be notified of changes etc. This would be a big improvement to the current option which is running command line programs and interpreting the stdout output.