Don't give up yet.
The usb_find_devices() should return devices with libusb driver, so problem might be there.
As you wrote, you cannot see "devices count: 1", which should appear.
In this phase of program, everything is in libusb0.dll "hands"
Did you try to make drivers for K4 and Touch separately? One driver for each?
Also this driver you have to generate when Kindle is in fastboot.
I have updated usb_windows.h , there was some fragments of code, which is no longer needed. For example adb_api.h is not needed and everything what has something in common with Adb library is not needed too.
Unfortunately I can't test the Touch, because I have not one and even don't know anyone who has it.