Scientific Definition Of Sailing Terms

[sea_casper]

If you're sailing in strong winds, where the wind shear (velocity difference) between the top and bottom of the sail is usually very small (unlike low winds), if adding "twist" to lessen heel adds to forward speed, I think it proves that your sail is trimmed/sheeted too tight, or you're footing excessively (sailing too low) if going close-hauled. If the sail was trimmed optimally before you got overpowered and let the top twist off to de-power, then the top should be luffing, trimmed looser than optimal, afterwards. The sail will then generate LESS forward force and power, not more. OTOH, if excessive heeling was slowing the boat down, it may still go faster with the extra twist, same as an overpowered boat that reefs.

You over analyzed what I said, I stated that AC wing sail engineers discovered that the twist element in a conventional sail, produced a forward thrust component, that wing sails don't replicate. I did not speculate under what wind conditions they were studying. A foiled catamaran has minimal "heel" unless they crash.
Like I said it's complicated, the resultant sail lift vector is the sum of vectors from sections of the sail, each having perhaps a different wind vector value and angle of attack, and then to make the analysis more complicated tilt the mast relative to the horizontal wind vector, then add to it and widen the boundary conditions, high winds, light winds, gusts etc. the brain overloads.
There is no optimum sail trim, only your personal best, for the moment or for a short period of time, you can go crazy trying to optimize, pick an average, sit back and enjoy. If winds are too light, leave sails up for visibility and turn on iron spinnaker, too windy, stay home, or furl and turn on motor, enjoy.