I guess you meant to write this as a reply to my post?
Well the data I have given does not show that the HTT-40 has an "unproven" design or anything. It just indicates there are multiple places where the design could have been optimized to extract maximum performance from the plane.
It doesn't affect flight safety or training effectiveness significantly.
The reason for not going forward with these optimizations is that it would have required significant rework of the aero components.
Similar hurdles were faced with the development of the HJT-36, of course also designed by HAL ARDC. Only difference being, the issues were significant enough that they were forced to take foreign consultation and then made changes to the plane itself that were more than addon stability devices.
It would require more R&D funding to the design team for them to be able to optimize the design further.
