BL-Touch bed leveling seems to produce tilted bed level around Y-axis
The problem with the Tevo Tornado design is that the design is as such that the Z-axis is powered by a single stepper (under the assumption that you have not added a second Z stepper).

This means that the level relies on the rigidity of the X-axis assembly, more specific the play on the guide wheels. Apparently the BL-Touch level determination suffers (the up and down movement while probing) from this design as can be seen from the tilt around the Y-axis direction. This effect causing the tilted level plane is called hysteresis. Now that the Z-axis moves up and down you experience much more problems than using a mechanical switch. The effect is more pronounced when the mass of the hot end carriage is furthest from the Z-axis lead screw.

Note that an extra stepper can also cause tilted level when the second stepper does not move in sync (e.g. missing steps). In such designs, a single stepper (geared) belt driven 2 lead screw has better performance in that respect.