Would the front rudder of the Wright brothers really have helped in recovering the glider from a stall? I have found a paragraph in the 1904 British patent of the Wright brothers (see the citation below) and it seems, from what they explain, that the two inventors believed the front rudder could have recovered the plane from a stall in any situation.

The question is, why were they so sure that after a stall the plane would have started to fall nose down, would have accelerated and the front rudder would have been able again to control the pitch of the flying machine?

If the main wings (and also the front rudder) had stalled their glider/airplane could have started to fall sideways or tail first.   


  "Contrary to the usual custom, we place the horizontal rudder in front
  of the main surfaces or “wings” at a negative angle, and use no
  horizontal tail at all. By this arrangement we obtain a forward
  surface which is almost free from pressure under ordinary conditions
  of flight, but which, even if not moved at all, becomes an efficient
  lifting surface whenever the speed of the machine is accidentally
  reduced very much below the normal, and thus largely counteracts that
  backward travel of the centre of pressure on the main surfaces or
  wings which has frequently been productive of serious injuries by
  causing the machine to turn downward and strike the ground head on."
   Wright brothers, “British Patent No. 6732, A.D. 1904 – Improvements in Aeronautical Machines”, Date of Application: 19th Mar., 1904, Accepted: 12th May, 1904.
  
  Wright glider
No, it would not have helped by itself.

What could prevent a stall or recover the aircraft from an incipient stall would be a counteracting movement of that canard surface, but that would need to be commanded by the pilot. It makes little difference if that control surface is ahead or behind the wing as long as it has enough lift potential left to produce the desired pitch down moment.

The way we understand stability today is that the aircraft will correct a deviation from the desired pitch attitude without pilot intervention. Using this definition, the Wright Flyers were unstable. Only by active and permanent corrections could straight flight be maintained. This is rather stressful and makes longer flights very tiring. Flying faster also can be ruled out because the speed of deviations goes up with flight speed, such that the human reaction time delays corrections too much and can even make them counterproductive.

The Wrights were correct that an unloaded surface gives them the highest control authority and, when moved in a correct and timely manner, helps to prevent a stall. However, placing that surface ahead of the wing comes with several disadvantages, loss of stability being only one of several. On the other hand, placing that lightly loaded surface at the rear results in a stable aircraft with better performance.