It's not possible to do this right now because of the JACK API itself, nothing else.
The issue is that you can change any settings after JACK is started, and there's no way to know the exact parameters used to start JACK.
So the device selected in the jack-configure dialog may sometimes not match the one you're using right now.
There's an easy workaround though - just enable "Use aliases" in the engine tab and "Hardware Aliases" in the driver tab.
Claudia will then use the device names instead of 'Hardware Playback', and in Catia just enable "1st aliases" option.
Wow. This explains a lot. My biggest frustration also (something which very nearly made a student completely give up on KXStudio multiple times) has been the confusion about device swapping. The thing is, he couldn't tell what was the setting to use because things looked right, and various setups resulted in JACK totally failing to start, crashing, programs failing, so setup in Claudia making it such that if he had the device plugged in or not it made the difference between it running at all or not, and it was baffling to try to sort out the problems. If he always used the same device and never unplugged it, this wouldn't happen, but that's not a reasonable situation.
I didn't know about these Alias options, but I found a bug with them. If I use hardware aliases with duplex then both devices are the same "HDA ATI SB" even though I am switching the input back and forth. If I turn off hardware alias, then instead of "capture" I see "hw:Device,0" for the USB and "hw:SB.0" for internal sound. This is at least distinct. I guess this is a bug: when I use duplex mode with hardware aliases, both the input and output get the alias of the output device
I also get totally confused about the JACK configure settings in Claudia vs Cadence (and Catia too, there also I can access a configure window!). It looks like both programs can set things but there's no way to tell which is actually doing things. They ought to mirror each other or otherwise be only in one place. And there's no "switch master" option in Claudia. All this is baffling.
Ok, I think that if the duplex mode naming bug is fixed, then the alias workaround is good, and that helps clarify things. Too bad about JACK API. Somehow that really ought to be fixed so that the settings in the configure actually reflect the status. This is a big problem, especially for newbies. Very confusing.