I might be wasting time here, but I think you are maybe just a different sort of person who communicates in a slightly atypical fashion, and perhaps you have a bit of baggage with past instructional experiences. It is sometimes necessary as a coach to change up the instructions you would usually give to cater to a particular individual. It probably happens quite often in fact on certain specific things that someone just doesn't quite get right away.In videos, high level players toss the ball to where they want to impact it. At toss release, the head is low and back, not near impact. For the kick serve, they move consideably so that their heads are about under impact but that is at a later tiem than the toss release. So the instruction is not correct and misleading due to the time of release and the later time of impact and the head movement.
In any case, I still stand by my statement that most people understand right away that the purpose of the toss is to get the ball to the contact location. So with that understanding the instruction of tossing over your head also has a clear intent. That intent doesn't change with the developing serve. The understandings build on each other. In my experience teaching probably over a hundred people to serve over the years I can't think of any issue with that instruction at all. In fact, the most common problem I run into is not language barrier with simple instructions like that, it's spacial awareness and proprioception. For some people those two things are extremely challenging.
In any case, I encourage people to experiment as well. There is never a one size fits all answer. In fact, going by video, especially where you only have one or two clear examples to study, is likely to produce misleading instructional goals for a proportion of players. Not everyone gets their best results with the most common example of a technique. This is why a lot of instruction is geared toward understanding of the racquet ball interaction. The other stuff is just finding the best way for a body to produce the most effective racquet ball collision possible.
Anyway, to state the instruction is not correct, IMO, is quite arrogant and presumptuous. I won't try to analyze the statements in your response literally with a willful ignorance of the underlying intent and context as that would be childish, but I hope you get the point. And, if not, then feel free to carry on as you see fit, as I do enjoy and agree with much of what you post.