In general, teachers are not trained to teach pronunciation. Most use the "repeat-after-me" method which is ineffective. A skilled pronunciation teacher usually has training in phonetics, phonology, and second language teaching methods.
Out of 1000 Spanish teachers and tutors on italki, I found a few hundred when I filtered the search on skills (pronunciation).
Out of 1000 Spanish teachers and tutors on italki, I found 12 when I filtered the search on country (Spain) and skills (linguistics).
A few of the 12 teachers mentioned university studies in linguistics or philology (another name for linguistics). Twelve is a small enough number that you could contact each of them, explain your goals, and ask them how they could help you.