For the USB system it is not off-line, that definitely makes it a cups issue.
It might be that the usb code does a check wrong, as "printing" to the file
/dev/usb/lp0 works.
Can you try to use the url: "file:/dev/usb/lp0"
it might help. The problem then is that is there are more printers
the order might change, and that shouldn't be the case with usb:/...
If the Kyocera can handle HP compatibility, you could try the hplip package.
(that's an intermediate between cups and hp printers).