On a film set where the movement is planned and predictable then the rails will of course be useful. I acknowledged that in my post and reinforced that fact in the post. Using rails in a natural environment where the movement of an object is often unpredictable is obviously not the intended use for rails.
I suggest, from the questions being asked on this forum, that the majority of posters are not professional cinematographic operators and therefore their aspirations for a follow mode for tracking are not what you are now aiming for in reality .
The reason why many people, including me, were attracted to the vertical app, way before P4 came on the market, was that we liked the idea of visual recognition tracking as the hope was that it would negate the need for a moving target to carry a responder device to be followed. Personally my main use of your app is for free flight around a static object. That is why I've continued to push for course lock to be introduced. It makes free flight around an object much easier to control,
Although it isn't important to me, It seems that you do not wish, or are not able, to introduce that follow functionality with the visual recognition tracking. Certainly the difficulty in holding track on anything for very long, except in ideal conditions might be the real limitation of the technology.
I hope it isn't but the slow progress on improving maintaining track on even a static object , in anything but good high clarity conditions, might indicate that may be the case.
In that case I fully understand why you are now targeting the professional film maker as the prime use for your application and I wish you every success in your venture.