Hi H!
Glad to hear it works now! The CCK should work if the MIDI interface you use it with is really "class compliant", meaning it does not need its' own specific driver should you connect it to a Mac or a PC. In MIDI Designer you can check the ports it has recognized from the Config in tab Connections under "Hardware and Virtual Destinations". If it's not there, the iPad apparently doesn't see the interface and thus it can't be can't be used by MD.
By the way: if you connect your 8P bi-directionally to the iPad - so MIDI IN *and* MIDI OUT, the 8P should send out the Sysex data of a patch the moment you select a patch. MIDI Designer should update all controls to match the current patch. Neat! I haven't done this myself yet, but that should be the case.
Have fun programming your JX-8P!
Rainer