If I’m able to play with adb as I want (somehow bypassing locked bootloader and TWRP installation), this serves me well in my current situation…
But this would be a security breach…
As you mentioned, having an unlocked bootloader, even with data encryption, is unsafe.
About that, do you still use an unlocked bootloader now? Or do you have another solution to be able to (e.g.) boot into TWRP?
I will try to contact directly the devs after having resolved my problem (maybe this breach is only available in the build I got).
Anyway, I will try to stop bothering you with stuff you can’t answer 
Thanks a lot for all the help you provided!