Thanks for your quick response.
I did it finally: flashed a clean fastboot of V12.1.6.0.RFNEUXM EEA, next flashed twrp-3.4.2B_toco_by.alex.msk1407 via fastboot. Reboot in alex twrp flashed OrangeFox-R11.1-toco-AndroidHQ254.zip, restart and flashed...