qjackctl actually integrates its native client/port name aliases, which predated by a long time the jack-metadata-pretty-names-whatever feature inception for a decade or so...
the said integration goes--or should go--like this: jack-metadata pretty-names will persist as native aliases as long qjackctl should be up and running; once saved there would be no need to you launch jack_property any long thereafter.
all that's absolutely expected!
qjackctl actually integrates its native client/port name aliases, which predated by a long time the jack-metadata-pretty-names-whatever feature inception for a decade or so...
the said integration goes--or should go--like this: jack-metadata pretty-names will persist as native aliases as long qjackctl should be up and running; once saved there would be no need to you launch jack_property any long thereafter.
cheers