After a few more problems, everything works well, and aside from maneuvering, I confirm that it's very pleasant on the road during tight turns at low speed or in the city on small streets. I also confirm that you don't notice the boost decreasing with speed; the steering wheel resistance is simply always well adapted to the speed.
I say problems because I thought I had only damaged one part of the first Yaris assembly and could keep the other with the adjustments I had made. As a result, it worked, but more when turning left than right, and in a straight line, if I let go of the steering wheel, it turned left by itself.
So I had to replace both parts and modify the way I assembled the two tubes to avoid welding, instead using 3 screws in tapped holes:
And here's the result when stationary:
So if anyone wants to do the same thing, BE CAREFUL: the torque sensor is fragile, and you must avoid impacts and not weld anything on the Yaris assembly side.
