I think you understand what you need to do to get the plane to fly in a straight line, and your reasoning for why it is required is correct (ie it's to do with spiralling air striking the fin, not a torque or centrifugal reaction). But, the thrust on the plane is definitely acting forwards (and a bit to the right)!

Newton once said that force = mass x acceleration. He was quite a clever guy because he also figured that every action (ie force) has an equal and opposite reaction (ie if I push you, you push me back).

So, the propeller accelerates a column of air backwards. The mass of the air being moved, multiplied by the acceleration of that air, gives you the force that the propeller is applying to the air. And because every action has an equal and opposite reaction, this results in a force (ie thrust) on the plane that acts forwards.

Therefore, the thrust on the plane is forwards, not backwards. If you want to think of it this way, you could say that the thrust on the air is backwards, which is why if you put your hand in the prop wash it gets pushed backwards. And therefore, if you rotate the engine to the right a bit, the air is being accelerated to the left a bit and you get a resulting force on the plane to the right.

The terms are indeed technically correct!

James