Running jack on ubuntu linux, oldish toshiba: Several cabbage instruments crapped out when I'd hit too many notes -- sometimes the first note. I'd then change the audio output to 'none', after which I could change it back to 'system' and start things working again.
What really worked was killing jack and going back to alsa with direct hardware output.
Finding the FileRecorder in the examples:Fileplayers section fixed my problem getting things to record. It doesn't record everything playing, but does record from any instrument you've connected to it on the Cabbage Patcher. A simple thing, but good to know!
The arppeggiator in the synths examples is a truly lovely instrument with too many knobs etc. But how does one clear its list of notes?