"How is this type of change described accurately among trained musicians ?"
This I was thinking about last night. Firstly, I don't think 'trained muscians' if you mean pro musicians really bother too much about the difference and could use the terms interchangeably, but this does not mean there is not a difference.
I think tonal centre and Tonic are one and the same.
Secondly the word mode means something completely different today, than it used to Jazz modes you probably know, but "Church" modes are different, some of them do fit into this system but some don't. Modes existed before the major/minor scale came to predominantce.
These things only matter if your say, programming a Gregorian Chant, or if you want to mess with your thinking on Giant steps (lol)
Anyways here is a link that does a decent job of going into the minutae
http://music.stackexchange.com/questions/6401/whats-the-difference-between-modal-music-and-tonal-musicThis music dictionary I find very comprehensive and useful for this sort of question, I have to use Chrome to get it to work though.
http://www.dolmetsch.com/musictheory31.htmZ