I have not forgotten the question. In fact, I am not sure you are right. I think "Shihan" (certainly) and "Sensei" (probably) do have a very close connection with teaching and I doubt whether the structure of the words (the putative original meaning of the characters) has such a strong influence on what they mean in contemporary Japanese.

I realise that evidence is needed and I am producing it in the form of a general article which deals with Japanese terms for teaching and learning. I have almost finished it and you will have it as soon as it is ready.