Now I have recently flashed stock-firmware (F320L 11c), rooted and installed CWM 18.104.22.168.
Interestingly I can´t access CWM via the hardware-keys either, just as the problem before with the stock recovery, but I can get into CWM if I use the adb command to boot into recovery.
But in order to do that the device must be fully functional and bootable, otherwise adb won´t work. I am a bit concerned that if anything happens and I were to soft-brick my device, I wouldn´t get into CWM-recovery any more, since it is not accessible via hardware key-combination, but only over the adb-command.
Anybody got an idea how to solve this issue?