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.

Good luck!