In addition to what @menschel has written:
The Believer can be moved in the air with the default values. As far as I remember, Arxangel made its first flight with the standard values without any problems. Another setup from this forum provides some orientation: MFE Believer, documenting setup.
The speed parameters still don’t fit, Airspeed_cruise with 12 m/s and Airspeed_min 9 m/s are clearly too low. The Scaling_Speed with 15 m/s could fit. But the fact that the pilot flew at full throttle and 33 most time does not fit at all.
I also don’t understand why you continued to define the ailerons as flaperons without defining a switch to operate them. Switch to Ailerons first. If everything works out, you can still bother with flaperons (which I don’t like for aerodynamic reasons with outboard ailerons, but that has nothing to do with this)
The docility in FBWA was very very sloppy throughout. Unfortunately, I can’t say exactly what led to the roll (CG ok ? aileron deflection wide enough ?). In any case, the integrator is gradually overflowing to the point where the roll occurs.
The pilot does the right thing and switches back to manual, but unfortunately he switches the engines off (by mistake, as he did on take-off) !!! With engine power he would have stayed up.
I wouldn’t be discouraged and next time fly manually first, see if everything works and then go to FBWA.
Rolf